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E  L  E  M  E  N  T  S 


OF 


AGEICTJLTUKAL  CHEMISTRY 


GEOLO  GY. 


BY 

JAMES  F.  W.  JOHNSTON,  M.A.,  F.R.SS.  L.  &  E. 

Honorary  Member  of  the  Royal  Agricultural  Society  of  England,  and 
Author  of  "  Lectures  on  Agricultural  Chemistry  and  Geology." 


WITH  A  COMPLETE  INDEX, 


AMERICAN     P  R  E  F  A  0  E, 
BY  SIMON  BROWN, 

K  I)  I  r  O  n      OF     T  H  V     N  K  W     K  N  G  I.  A  N  D     F  A  R  M  K  >  . 


NEW-YORK : 
ORANGE    JUDD    &    CO.,    4  1     PARK     ROAV. 


Entered  according  to  Act  of  Congress,  in  tlio  year  1853,  by 

C.  if.  SAXTOX, 

m  the  Clerk's  OfBce  of  liio  District  Court  of  the  United  States  for  the  Soatli- 
em  District  of  Now  York. 


PREFACE  TO  THE  AMERICAN  EDITION. 


In  England,  and  on  the  continent  of  Europe,  it  has  been 
long  understood  among  the  class  who  own  the  soil,  and  culti- 
vate it  by  the  sweat  of  the  brow  of  other  men,  and  not  their 
personal  labor,  that  success  in  husbandry  must  depend  upon 
giving  to  the  soil,  in  some  form,  what  is  annually  taken  away 
in  cultivated  crops. 

In  America,  in  the  older  States,  the  same  truth  is  at  length 
reluctantly  admitted.  The  census  tables  have  shown  that  the 
wheat  crop  of  New  York,  in  some  counties,  has  fallen  in  its 
average  product  so  low  as  tight  bushels  to  the  acre,  where  for- 
merly from  thirty  to  forty  were  produced.  Lands  deemed  inex- 
haustible have  been  cropped  almost  to  barrenness.  Large  sec- 
tions of  territory  in  Yirginia,  formerly  very  productive,  by  a 
course  of  culture  not  guided  by  a  correct  knowledge  of  the 
scknu  of  Husbandry,  have  become  utterly  unproductive,  and 
been  abandoned  by  the  original  cultivators.  A  succession  of 
tobacco  crops  raised  by  shoal  plowing  without  artificial  manur- 
ing, or  a  proper  rotation  with  other  products,  exhausted  the 
mrface  soil,  and  compelled  the  proprietors  to  seek  fresh  fields. 
Recently  a  more  thorough  and  intelligent  system,  by  men  who 
are  both  owners  of  the  land  and  laborers  upon  it,  has  shown 
that  it  was  only  with  unreasonable  demands  upon  her  resources 


IV  PREFACE. 

that  a  generous  mother  Earth  had  refused  to  comply;  for  the 
same  lands,  by  deep  plowing  and  judicious  rotation,  are  yielding 
already  a  rich  return  for  labor  and  capital  to  their  owners. 

In  both  countries  it  is  now  regarded  by  well-informed  men  as 
settled,  that  only  labor  directed  by  scientific  knowledge  can 
yield  a  fair  return  upon  any  but  new  lands,  where,  as  in  our 
Western  States,  Nature's  storehouses  of  fertilizers  are  yet  unex- 
hausted. In  England  the  soil  is  owned  by  a  few,  and  those 
mostly  educated  men,  and  they,  durectly  or  indirectly,  insist 
upon  systematic  and  thorough  tillage,  as  the  only  means  of 
deriving  profit  from  their  capital. 

In  America,  in  the  free  States,  the  land  owner  labors  with 
his  own  hands,  and  a  knowledge  of  the  principles  of  husbandry 
must  be  generally  diffused,  that  each  for  himself  may  apply 
them  in  his  own  practice.  Indeed,  it  seems  peculiarly  fitting 
that  the  owner  of  the  soil,  who  himself  performs  the  labor  upon 
it,  should  have  constantly  in  view  the  reason  for  the  various 
processes  he  performs  in  bringing  his  crops  to  maturity. 

No  writer,  perhaps,  of  the  present  day,  has  succeeded  so 
well  as  Mk.  Johnston,  in  adapting  to  the  apprehension  of  the 
general  reader  his  teachings  upon  the  Science  of  Agriculture, — 
in  combining  with  instructions  necessarily  abstruse,  the  practi- 
cal ideas  which  make  his  theories  of  manifest  present  value  to 
the  farmer.  His  style  has  the  simplicity  and  directness  only 
acquired  by  those  accustomed  to  speak  to  practical  men.  He 
announces  at  once  his  object, — ^the  advantage  to  be  gained  ; 
and  then  tells  us  in  the  plainest  language  how  to  attain  it. 

More  advancement  has  been  made  in  Agricultural  Chemistry 
in  the  last  ten  years,  than  in  any  other  branch  of  Science,  and 
DO  mind  is  better  qualified  than  Mr.   Johnston's,  to  seize  upon 


PREFACE.  T 

every  new  theory  and  fact,  and  to  combine  them  all  into  a  har- 
monious whole. 

The  present  volume  pretends  to  no  great  recent  discoveries 
in  Agriculture,  but  it  is  believed  that  in  no  other  work  have 
the  results  of  experience  and  theories  been  more  carefully  com- 
pared. 

The  writer,  in  addition  to  a  complete  treatise  upon  the 
Elements  of  Agricultural  Chemistry,  suggests  modes  of  thought 
calculated  to  lead  the  reader  constantly  to  reflection.  What 
each  crop  and  each  rotation  of  crops  takes  from  the  soil,  is 
carefully  shown,  that  so  the  farmer  may  be  led  to  inquire  how 
he  can  return  the  elements  thus  exhausted.  Exact  analyses  are 
given  of  the  various  substances  used  as  manure,  thus  giving  aid 
to  answer  such  inquiries.  The  structure  of  the  various  parts  of 
plants,  the  stem,  root,  and  leaves,  and  their  various  functions, 
are  also  carefully  considered,  with  a  view  of  ascertaining  both 
how  their  growth  may  be  promoted,  and  to  what  useful  pur- 
poses they  may  be  appUed  as  manure,  when  their  other  uses  are 
exhausted. 

The  structure  of  the  earth,  of  its  various  rock  formations, 
which  are  the  foundation  of  all  soils,  is  lucidly  discussed,  giving 
an  insight  into  the  value  of  geology  as  a  practical  helper  in 
husbandry — giving  us  at  the  same  time  direct  instruction  in  the 
best  mechanical  treatment  of  the  farm,  in  plowing,  subsoiling, 
and  thorough  draining. 

The  reader  will  find  practical  advantage  in  the  suggestions  of 
the  author  as  to  adulterations  of  the  various  fertilizers  now  ex- 
tensively used  in  this  country,  especially  of  guano.  It  is  believed 
that  gross  impositions  are  already  practiced  upon  the  agricultu- 
ral community,  in  the  sale  of  various  articles  of  little  value.  It 
is  only  by  the  aid  of  scientific  men,  like  our  author,  that  these 


?1  PREFACI. 

frauds  can  be  detected,  and  the  community  be  protected  from 
imposition,  while  they  reap  the  full  advantage  to  be  derived 
from  the  use  of  those  articles  when  honestly  supplied  to  them 
in  a  pure  form.  The  work  is  offered  to  the  public,  not  to  su- 
persede the  truly-scientific  and  more  technical  treatise  of  Stock- 
hardt  in  the  schools  and  colleges,  not  indeed  to  take  the  place 
of  any  existing  work,  even  in  our  libraries,  but  as  containing  the 
matured  results  of  a  carefully-trained  mind,  which  has  long 
compared  the  practical  notions  of  the  farmer  with  the  theoreti- 
cal ideas  of  the  chemist  and  geologist,  and  so  yrrought  out  a 
fund  of  valuable  knowledge  for  practical  men,  such  as,  it  is  be- 
lieved, no  other  book  supplies. 

Another  feature  of  great  value  to  the  work  is  that  it  has  a 
thoroughly-digested  analytical  and  alphabetical  index,  so  that 
the  editor,  or  student,  in  discussing  any  particular  subject  here- 
in treated,  may  turn  directly  to  it  ;  or  the  farmer,  when  in  doubt 
as  to  the  treatment  or  composition  of  certain  soils,  the  compost- 
ing or  application  of  manures,  or  the  fertilizing  properties  of  the 
rocks  upon  his  farm,  by  the  aid  of  the  index  is  directly  referred 
to  the  subject  in  question,  where  he  will  usually  find  such  plain 
and  practical  suggestions  as  will  enable  him  to  derive  important 
aid  in  Lis  operations. 

SmoK  Bbowk. 
Bofftm,  1863. 


Il^HODUCTION. 


The  scientific  principles  npon  which  the  art  of  culture  depends, 
have  not  hitherto  been  suflSciently  understood  or  appreciated 
by  practical  men.  Into  the  causes  of  this  I  shall  not  here  in- 
quire. I  may  remark,  however,  that  if  Agriculture  is  ever  to 
be  brought  to  that  comparative  state  of  perfection  to  which 
many  other  arts  have  already  attained,  it  will  only  be  by  avail- 
ing itself,  as  they  have  done,  of  the  many  aids  which  science 
offers  to  it.  And  if  the  practical  -man  is  ever  to  realise  upon 
his  farm  all  the  advantages  which  science  is  capable  of  placing 
within  his  reach,  he  must  become  so  far  acquainted  with  the 
connection  that  exists  between  the  art  by  which  he  lives  and 
the  sciences,  especially  of  Chemistry,  Geology,  and  Chemical 
Physiology,  as  to  be  prepared  to  listen  with  candor  to  the 
suggestions  they  are  ready  to  make  to  him,  and  to  attach  their 
proper  value  to  the  explanations  of  his  various  processes  which 
they  are  capable  of  affording. 

The  following  little  Treatise  is  intended  to  present  a  familiar 
outline  of  the  rabjects  treated  of  more  at  large  in  my  publishe'd 


Vm  IXTRODUCTIOX. 

Lectdres  on  Agricultural  Chemistry  and  Geologt.  What, 
in  this  work,  has  necessarily  been  taken  for  granted,  or  briefly 
noticed,  is  in  the  Lectures,  examined,  discussed,  or  more  folly 
detailed. 

Those  who  wish  to  put  into  the  hands  of  the  young  a  still 
more  condensed  view  of  the  principles  of  scientific  agriculture, 
n'ill  find  it  in  my  Catechism  of  Agricultural  Chemistry  and 
Geology.  To  most  persons,  indeed,  it  will  prove  advantageous 
to  read  the  Catechism  first,  and  to  proceed  from  it  to  the  EUi- 
menis,  and  then  to  the  Lectures. 

DuBHAH,  November  1852. 


ELEMENTS 

OP 

AGRICULTURAL  CHEMISTRY 


CHAPTER  I. 


Object  of  the  farmer. — "What  chemistry,  geology,  and  chemical  physiology 
may  do  for  agriciilture. — Distinctiou  between  organic  and  inorganic  sub- 
stances.— The  ash  of  plants  and  animals. — Simple  and  compound  bo- 
dies.— "What  elementary  bodies  are  contained  in  the  organic  part  of 
soils,  plants,  and  animals. — Properties  of  carbon,  sulphur,  phosphorus, 
hydrogen,  oxygen,  and  nitrogen. — Relative  proportions  of  these  elemen- 
tary bodies  contained  in  plants  and  animals. — Meaning  of  chemical  com- 
bination and  chemical  decomposition. 

The  object  of  the  practical  farmer  is  to  raise  from  a  given 
extent  of  land  the  largest  quantity  of  the  most  valuable  pro- 
duce at  the  least  cost,  in  the  shortest  period  of  time,  and  with 
the  least  permanent  injury  to  the  soU.  Chemistry,  Geology, 
and  Chemical  Physiology  throw  light  on  every  step  he  takes, 
or  ought  to  take,  in  order  to  effect  this  main  object. 

SECTION   I. WHAT   CHEMISTRY,  GEOLOGY,    AND   CHEMICAL   PHYSIO- 
LOGY  MAY   HOPE   TO   DO    FOB   AGRICULTUBE. 

But  there  are  certain  definite  objects  which,  in  their  connec- 
tion with  agriculture,  these  sciences  hope  to  attain.  Thus, 
without  distinguishing  the  special  province  of  each,  they  pro- 
pose generally : — 


I  WHAT   CHEMISTKY   AND   GEOLOGY 

1".  To  collect,  to  investigate,  and,  if  possible,  to  crplain  till 
known  facts  in  practical  husbandry. — This  is  their  first  duty — a 
laborious,  difficult,  but  important  one.  Many  things  which  are 
received  as  facts  in  agriculture,  prove  to  be  more  or  less  uutrue 
when  investigated  and  tested  by  experiment.  Many  ascertained 
facts  appear  inexplicable  to  the  uninstructed — many  even  oppo- 
site and  contradictory,  which  known  principles  clear  up  an  J 
reconcile — ^yet  there  are  many  more  which  only  prolonged  re- 
search can  enable  us  to  explain  1 

2°.  From  observations  and  experiments  made  in  the  field  or  in 
the  laboratory,  to  deduce  principles  which  may  be  more  or  less  appli- 
cable in  all  circumstances. — Such  principles  will  explain  useful 
practices,  and  confirm  their  propriety.  They  will  also  account 
for  contradictory  results,  and  will  point  out  the  circumstances 
under  which  this  or  that  practice  may  most  prudently  and  'mq'^i 
economically  be  adopted. 

Armed  with  the  knowledge  of  such  principles,  the  iustriicted 
farmer  will  go  into  his  fields  as  the  physician  goes  to  the  bed- 
side of  his  patient, — prepared  to  understand  symptoms  and 
appearances  he  has  never  before  seen,  and  to  adapt  his  prac- 
tice to  circumstances  which  have  never  before  fallen  under  his 
observation. 

To  deduce  principles  from  collections  of  facts  is  attended 
with  much  difficulty  in  all  departments  of  knowledge.  In  agri- 
culture it  is  at  present  an  unusually  difficult  task.  Observations 
and  experiments  in  the  field  have  hitherto  been  generally  made 
with  too  little  care,  or  recorded  with  too  little  accuracy,  to 
justify  the  scientific  man  in  confidently  adopting  them  as  the 
basis  of  his  reasonings.  A  new  race,  however,  of  more  careful 
observers,  and  more  accurate  experimenters,  is  now  springing 
up.  By  their  aid,  the  advance  of  sound  agricultural  know- 
ledge cannot  fail  to  be  greatly  promoted. 

3°.  To  suggest  improved,  and,  per /taps,  previously  unlhougkt-of 
tiethods  of  fertilising  the  soil. — A  true  explanation  of  twenty 
known  facts  or  results,  or  useful  practices,  should  suggest  nearlj 


MAY   HOPE   TO   DO    FOR   AGRICULTURE.  8 

as  many  more.  Thus  the  explanation  of  old  errors  will  not 
only  guard  the  practical  man  from  falling  into  new  ones,  but 
will  suggest  direct  improvements  he  would  not  otherwise  have 
thought  of.  So,  also,  the  true  explanation  of  one  useful  prac- 
tice will  point  out  other  new  practices,  which  may  safely  and 
with  advantage  be  adopted. 

4°.  To  analyse  soils,  manures,  and  vegetable  products. — This  is 
a  most  laborious  department  of  the  duties  which  agriculture 
expects  chemistry  to  undertake  in  her  behalf. 

a.  Soils. — The  kind  and  amount  of  benefit  to  be  derived  from 
the  analyses  of  soils,  are  becoming  every  day  more  apparent. 
We  cannot,  indeed,  from  the  results  of  an  analysis,  prescribe  in 
every  case  the  kind  of  treatment  by  which  a  soil  may  at  once 
be  rendered  most  productive.  In  many  cases,  however,  certain 
wants  of  the  soil  are  directly  pointed  out  by  analysis  ;  in  many 
others,  modes  of  treatment  are  suggested,  by  which  a  greater 
fertility  is  likely  to  be  produced, — and,  as  our  knowledge  of 
the  subject  extends,  we  may  hope  to  obtain,  in  every  case, 
some  useful  directions  for  the  improvement  or  more  profitable 
culture  of  the  land. 

b.  Manures. — Of  the  manures  we  employ,  too  much  cannot 
be  known.  An  accurate  knowledge  of  these  will  guard  the 
practical  man  against  an  improvident  waste  of  any  of  those 
natural  manures  which  are  produced  upon  his  farm — thus  les- 
sening the  necessity  for  foreign  manures,  by  introducing  a 
greater  economy  of  those  he  already  possesses.  It  will  also 
protect  him  against  the  ignorance  or  knavery  of  the  manure 
manufacturer.  The  establishment  of  such  manufactories,  con- 
ducted by  skilful  and  honorable  men,  is  one  of  the  most  impor- 
tant practical  results  to  which  the  progress  of  scientific  agricul- 
ture is  likely  to  lead.  And  if  it  cannot  prevent  unscrupulous 
adulterators  from  engaging  in  this  new  traffic,  chemistry  can  at 
least  detect  and  expose  their  frauds. 

c.  Vegetable  Products. — In  regard,  again,  to  the  products  of 
the  soil,  few  things  are  now  more  necessary  than  a  rigorous 


4  WHAT   CHEMISTRY   AND   GEOLOGY    MAY   HOPE   TO   DO,  &C. 

analysis  of  all  their  parts.  If  we  know  what  a  plant  contains, 
we  know  what  elementary  bodies  it  takes  from  the  soil,  and, 
consequently,  what  the  soil  must  contain,  if  the  plant  is  to  grow 
upon  it  in  a  healthy  manner, — that  is,  we  shall  know,  to  a  cer- 
tain extent,  how  to  manure  it.  . 

On  the  other  hand,  in  applying  vegetable  substances  to  the 
feeding  of  stock,  it  is  of  equal  importance  to  know  what  they 
severally  contain,  in  order  that  a  skilful  selection  may  be  made 
of  such  kinds  of  food  as  may  best  suit  the  purposes  we  intend 
them  to  serve. 

5°.  To  explain  how  plants  grow  and  are  nourished,  and  how 
animals  are  supported  and  most  cheaply  fed. — What  food  plants 
require,  and  at  different  periods  of  their  growth,  whence  they 
obtain  it,  how  they  take  it  in,  and  in  what  forms  of  chemical 
combination  ?  Also,  what  kind  and  quantity  of  food  the 
animal  requires,  what  purposes  different  kinds  of  food  serve  iu 
the  animal  economy,  and  how  a  given  quantity  of  any  variety 
of  food  may  be  turned  to  the  best  account  ?  What  questions 
ought  more  to  interest  the  practical  farmer  than  these  ? 

Then  there  are  certain  peculiarities  of  soil,  both  physical  and 
chemical,  which  are  best  fitted  to  promote  the  growth  of  each 
of  our  most  valuable  crops.  There  are  also  certain  ways  of 
cultivating  and  manuring,  and  certain  kinds  of  manure  which 
are  specially  favorable  to  each,  and  these  again  vary  with  every 
important  modification  of  climate.  Thus  chemical  physiology 
has  much  both  to  learn  and  to  teach  in  regard  to  the  raising 
of  crops. 

So,  different  kinds  and  breeds  of  domestic  animals  thrive  best 
upon  different  kinds  of  food,  or  require  different  proportions  of 
each,  or  to  have  it  prepared  in  different  ways,  or  given  at  differ- 
ent times.  Among  animals  of  the  same  species  also,  the  grow- 
ing, the  full-grown,  the  fattening,  and  the  milking  animal,  re- 
spectively require  a  peculiar  adjustment  of  food  iu  kind,  quan- 
tity, or  form.  All  such  adjustments  the  researches  of  chemistry 
and  physiology  alone  enable  us  accurately  to  make. 


ORGANIC   AND   INORGANIC   PARTS    OF    PLANTS,  &C.  b 

6°.  To  test  the  opinions  of  theoretical  men. — Erroneous  opinions 
lead  to  grave  errors  in  practice.  Such  incorrect  opinions  are 
not  unfrequently  entertained  and  promulgated  even  by  eminent 
scientific  men.  They  are  in  this  case  most  dangerous  and  most 
difficult  to  overturn  ;  so  that  against  these  unfounded  theories 
the  farmer  requires  protection,  no  less  than  against  the  quack- 
ery of  manufactured  manures.  It  is  only  on  a  basis  of  often 
repeated,  skilfully  conducted,  and  faithfully  recorded  experi- 
ments, made  by  instructed  persons,  that  true  theories  can  ever 
be  successfully  built  up.  Hence  the  importance  of  experiments  in 
practical  agriculture. 

Such  are  the  principal  objects  which  chemistry,  aided  by  geo- 
logy and  physiology,  either  promises  or  hopes  to  attain.  In  no 
district,  however,  will  the  benefits  she  is  capable  of  conferring 
upon  agriculture  be  fully  realised,  unless  her  aid  be  really  sought 
for,  her  ability  rightly  estimated,  and  her  interference  earnestly 
requested.  In  other  words,  what  we  already  know,  as  well  as 
what  we  are  every  day  learning,  must  be  adequately  diffused 
among  the  agricultural  body,  and  in  every  district  means  must 
be  adopted  for  promoting  this  diffusion.  It  is  in  vain  for  che- 
mistry and  the  other  sciences  to  discover  or  suggest,  unless  her 
discoveries  and  suggestions  be  fully  made  known  to  those  whose 
benefit  they  are  most  likely  to  promote. 

SECTION   II. OF   ORGANIC  AND  INORGANIC  MATTER,  AND  OF  THE  OR- 
GANIC  AND   INORGANIC   PARTS    OF   ANIMALS,  PLANTS,  AND   SOILS, 

In  the  prosecution  of  his  art,  two  distinct  classes  of  substances 
engage  the  attention  of  the  practical  farmer — the  living  animals 
and  crops  he  raises,  and  the  dead  soils  from  which  the  latter 
are  gathered.  If  he  examine  any  fragment  of  an  animal  or 
vegetable,  either  living  or  dead, — a  piece  of  flesh  or  wood,  for 
example, — he  will  observe  that  it  exhibits  pores  of  various 
kinds  arranged  in  a  certain  order  ;  that  it  has  a  species  of  inter- 
nal structure  ;  that  it  has  various  parts  or  organs ;  in  short, 


6  ORGANIC   AND   INORGANIC   PARTS    OF    PLANTS,  &C. 

that  it  is  what  physiologists  term  organised.  If  he  examine,  in 
like  manner,  a  lump  of  earth  or  rock,  he  will  perceive  no  such 
structure.  To  mark  this  distinction,  the  parts  of  animals  and 
vegetables,  either  living  or  dead — whether  entire  or  in  a  state 
of  decay — are  called  organic  bodies,  while  earthy  and  stony  sub- 
stances are  called  inorganic  bodies. 

Organic  substances  are  more  or  less  readily  burned  away  and 
dissipated  by  heat  in  the  open  air  ;  inorganic  substances  are 
generally  fixed  and  permanent  in  the  fire. 

Kow  the  crops  which  grow  upon  the  land,  as  well  as  the  soil 
in  which  they  are  rooted,  contain  a  portion  of  both  of  these 
classes  of  substances.  In  all  fertile  soils  there  exists  from  3  to 
10  per  cent,  of  vegetable  or  other  matter,  of  organic  origin.  If 
we  heat  a  portion  of  such  a  soil  to  redness  in  the  open  air,  as 
in  the  annexed,  (fig.  1,)  this  organic  matter  will  burn  away, 
leaving  the  inorganic  or  mineral  matter  behind.  By  this  burn- 
ing, most  soils  are  changed  in  color,  but,  if  previously  dried, 

Fig.  1. 


are  not  materially  diminished  in  bulk.    The  inorganic  matter 
forms  by  far  their  largest  part. 

All  vegetables,  again,  as  they  are  collected  for  food,  leave, 
when  burned,  a  sensible  quantity  of  inorganic  ash  ;  but  of  them 
it  forms  only  a  small  part.  Wood  leaves  about  a  ^  per  cent, 
grain  2  or  3  per  cent,  straw  about  5  per  cent ;  and  only  in 
rare  cases  does  the  ash  left  amount  to  15  or  20  per  cent  of  the 
weight  of  a  vegetable  substance.  Hence,  when  a  handful  of 
wheat,  wheat  straw,  hay,  &c.,  is  burned  in  the  air,  a  compara- 
tively small  weight  of  matter  only  remains  behind.    Every  one 


SIMPLE   AND    COMPOUND    BODIES,  T 

i»  familiar  with  this  fact  who  has  seen  the  small  bulk  of  ash  that 
is  left  wlieii  weeds,  or  thorn-bushes,  or  trees,  are  burned  in  the 
field,  or  when  a  hay  or  corn  stack  is  accidentally  consumed. 
Yet  this  ash  is  very  important  to  the  plant,  and  the  study  of  its 
true  nature  throws  much  light,  as  we  shall  hereafter  see,  on  the 
practical  management  of  the  land  on  which  any  given  crop  is  to 
be  made  to  grow.  It  strikes  us  also  as  being  important  in 
quantity,  when  we  consider  how  much  may  be  contained  in  an 
entire  crop.  Thus  the  quantity  of  ash  left  by  a  ton  of  wheat 
straw  is  sometimes  as  much  as  360  lb.,  and  by  a  ton  of  oat  straw 
as  much  as  200  lb.  A  ton  of  the  grain  of  wheat  leaves  on  an 
average  about  45  lb.,  of  the  grain  of  oats  about  9  lb.,  and  of 
oak  wood  only  4  or  5  lb. 

Animal  substances  also  leave  a  proportion  of  ash  when  burned 
in  the  air.  Dry  flesh  and  hair  leave  about  5  per  cent  of  their 
weight  of  inorganic  ash  ;  dry  bones  more  than  half  their  weight. 

Generally,  therefore,  the  soil  contains  little  organic  and  much 
inorganic  or  mineral  matter — the  plant  much  organic  and  little 
mineral — the  animal,  in  its  soft  parts,  little,  in  its  hard  or  solid 
parts,  much  mineral  matter. 

SECTION    III. OF    SIMPLE    OR    ELEMENTARY   AND    COMPOUND    BODIES. 

The  various  kinds  of  organic  and  inorganic  matter  of  which 
soils,  plants,  and  animals  consist,  are  distinguished  by  chemists 
into  two  groups.  Those  which,  by  the  agency  of  heat,  or  by 
any  chemical  or  other  means,  can  be  separated  into  two  or  more 
unlike  kinds  of  matter,  are  called  compound  bodies — those  which 
cannot  be  so  separated,  are  called  simple  or  elementary  bodies. 

Gold,  iron,  sulphur,  and  pure  charcoal  are  simple  substances. 
They  cannot  by  any  known  means  be  separated  or  resolved  into 
more  than  one  substance. 

Wood,  flesh,  limestone,  sand,  &c.,  are  compound  substances. 
We  are  acquainted  with  methods  by  which  they  can  each  be 
split  up  into  two  or  more  substances  different  from  each  other. 


I  PROPERTIES    OF    CARBON 

and  from  the  wood  or  flesh,  &c.,  from  which  they  are  ob- 
tained. 

Of  simple  or  elementary  bodies  sixty-four  are  at  present 
known  to  chemists.  All  the  other  forms  of  matter  which  occur 
in  the  animal,  vegetable,  or  mineral  kingdoms  are  compound. 

SECTION    IV. OF    THE    ELEMENTARY    SUBSTANCES    OF    WHICH    THE 

ORGANIC   PART    OF    SOILS,    PLANTS,    AND   ANIMALS    CONSISTS. 

The  organic  or  combustible  part  of  soils,  plants,  and  animals 
is  composed  almost  exclusively  of  four  elementary  substances, 
known  to  chemists  by  the  names  of  carbon,  hydrogen,  oxygen, 
and  nitrogen.  It  usually  contains  also  a  minute  proportion  of 
sulphur  and  phosphorus. 

Of  these,  carbon,  sulphur,  and  phosphorus  are  solid  substances  ; 
while  hydrogen,  oxygen,  and  nitrogen  are  gases,  or  peculiar 
kinds  of  air.     Their  properties  are  as  follows  : — 

1.  Carbon. — When  wood  is  burned  in  a  covered  heap,  as  is 
done  by  the  charcoal  burners, — or  is  distilled  in  iron  retorts,  as 
in  making  wood-vinegar, — it  is  charred,  and  is  converted  into 
common  wood  charcoal.  This  charcoal  is  the  most  usual  and 
best  known  variety  of  carbon.  It  is  black,  soils  the  fingers,  and 
is  more  or  less  porous,  according  to  the  kind  of  wood  from  whiclr 
it  has  been  formed.  Coke  obtained  by  charring  or  distillin* 
coal  is  another  variety.  It  is  generally  denser  or  heavier  than 
charcoal,  though  usually  less  pure.  Black  lead  is  a  third  va- 
riety, still  heavier  and  more  impure.  The  diamond  is  the  only 
form  in  which  carbon  occurs  in  nature  in  a  state  of  perfect 
purity. 

This  latter  fact,  that  the  diamond  is  pure  carbon — that  it  is 
essentially  the  same  substance  with  the  finest  and  purest  lamp- 
black— is  very  remarkable  ;  but  it  is  only  one  of  the  numerous 
striking  circumstances  that  every  now  and  then  present  them- 
selves before  the  inquiring  chemist. 

Charcoal,  the  diamond,  lamp-black,  and  all  the  other  fornu 


PROPERTIES    OF   HTDROGEN. 


ft 


of  carbon,  burn  away  more  or  less  slowly  when  heated  to  red- 
ness in  the  air  or  in  oxygen  gas,  and  are  converted  into  a  kind 
of  gas  known  by  the  name  of  carbonic  acid  gas.  The  impure 
varieties,  when  bui'ned,  leave  behind  them  a  greater  or  less  pro- 
portion of  ash. 

2.  Sulphur  is  a  well  known  solid  substance  of  a  light  yellow 
color,  and  faint  peculiar  odor.  It  burns  with  a  pale-blue 
flame,  and  in  burning  gives  off  fumes  possessed  of  a  strong  pun- 
gent characteristic  smell.  , 

3.  Phosphorus  is  a  yellowish  waxy  substance  of  a  peculiar 
smell,  which  smokes  in  the  air,  shines  in  the  dark,  takes  fire  by 
mere  rubbing,  and  burns  with  a  large  bright  flame  and  much 
white  smoke.  Like  sulphur,  it  exists  in  all  plants  and  animals, 
though  in  comparatively  small  quantity.  Like  sulphur,  also,  it 
is  employed  largely  in  the  arts,  especially  in  the  manufacture  of 
lucifer  matches. 

4.  Hydrogen. — If  oil  of  vitriol  (sulphuric  acid)  be  mixed 

Fig.  2. 


with  twice  its  bulk  of  water,  and  be  then  poured  upon  iron 
filings,  or  upon  small  pieces  of  zinc,  the  mixture  will  speedily 
begin  to  boil  up,  and  bubbles  of  gas  will  rise  to  the  surface  of 
the  liquid  in  great  abundance.  These  are  bubbles  of  hydrogen  gas. 


1* 


10  PROPERTIES   OP   OXYGEN. 

If  the  experiment  be  performed  in  a  bottle,  the  hydrogen 
which  is  produced  will  gradually  drive  out  the  atmospheric  air 
it  contained,  and  will  itself  take  its  place.  If  a  taper  be  tied 
to  the  end  of  a  wire,  and,  when  lighted,  be  introduced  into  the 
bottle,  (fig.  2,)  it  will  be  instantly  extinguished  ;  while  the 
hydrogen  will  take  fire,  and  burn  at  the  mouth  of  the  bottle 
with  a  pale  yellow  flame.  If  the  taper  be  inserted  before  the 
common  air  is  all  expelled,  the  mixture  of  hydrogen  and  com- 
mon air  will  burn  with  an  explosion  more  or  less  violent,  and 
may  even  shatter  the  bottle  and  produce  serious  accidents. 
This  experiment,  therefore,  ought  to  be  made  with  caution.  It 
may  be  more  safely  performed  in  a  common  tumbler,  (fig.  3,) 

TiS.  3. 


covered  closely  by  a  plate,  till  a  sufficient  quantity  of  hydrogen 
is  collected,  when,  on  the  introduction  of  the  taper,  the  light 
will  be  extinguished,  and  the  hydrogen  will  burn  with  a  less 
violent  explosion.  Or  the  gas  may  be  prepared  in  a  retort,  and 
collected  over  water,  as  shown  in  fig.  4. 

This  gas  is  the  lightest  of  all  known  substances,  rising  through 
common  air  as  wood  does  through  water.  Hence,  when  con- 
fined in  a  bag  made  of  silk,  or  other  light  tissue,  it  is  capable 
of  sustaining  heavy  substances  in  the  air,  and  even  of  carrying 
them  up  to  great  heights.  For  this  reason  it  is  employed  for 
filling  and  elevating  balloons. 

Hydrogen  gas  is  not  known  to  occur  any  where  in  nature  in 
any  sensible  quantity  in  a  free  state.  It  is  very  abundant  in 
water,  and  in  many  other  substances,  in  what  by  chemists  is 
called  a  state  of  combination.     (See  pages  15  and  24.) 

5.  Oxygen — ^When  strong  oil  of  'ritriol  is  poured  upon  black 


PROPERTIES    OF    OXYGEN.  11 

oxide  of  manganese,  and  heated  in  a  glass  retort,  (fig.  4,)  or 
when  a  mixture  of  chlorate  of  potash  with  an  equal  weight  of 


Fig.  4. 


oxide  of  manganese,  or  when  chlorate  of  potash  alone,  or  red 
oxide  of  mercury  alone,  is  so  heated — or  when  saltpetre,  or  the 
black  oxide  of  manganese,  is  heated  alone  in  an  iron  bottle, — 
in  all  these  cases  a  kind  of  air  is  given  off,  to  which  the  name 
of  oxygen  gas  is  given.  It  is  obtained  with  the  greatest  ease, 
rapidity,  and  purity,  from  the  mixture  of  chlorate  of  potash  and 
oxide  of  manganese. 

A  very  elegant  method  of  preparing  the  gas  is  to  put  a  few 

Fig.  5. 


grains  of  red  oxide  of  mercury  into  a  tube,  and  apply  the  l^eat  of 
a  lamp  as  in  fig.  5.  Oxygen  gas  will  be  given  off  while  minute 
globules  of  metallic  mercury  will  condense  on  the  cool  part  of 
the  tube.    The  presence  of  oxygen  in  the  tube  is  shown  by  in- 


Hi  PREPARATIOX    OF   NITROGEN. 

troducing  iuto  one  end  of  it  a  half-kindled  match,  when  it  will 
be  seen  to  burn  up  brilliantly. 

It  is  the  characteristic  property  of  this  gas,  that  a  taper, 
when  introduced  into  it,  burns  with  great  rapidity,  and  with  ex- 
ceeding brilliancy,  and  continues  to  burn  till  either  the  whole  of 
the  gas  disappears  or  the  taper  is  entirely  consumed.  In  this 
respect  it  differs  both  from  hydrogen  and  from  common  air.  If 
a  living  animal  is  introduced  into  this  gas,  its  circulation  and 
its  breathing  become  quicker — it  is  speedily  thrown  into  a  fever 
— it  lives  as  fast  as  the  taper  burned — and,  after  a  few  hours, 
dies  from  excitement  and  exhaustion.  This  gas  is  not  lighter, 
as  hydrogen  is,  but  is  about  one-ninth  part  heavier  than  com- 
mon air. 

In  the  atmosphere,  oxygen  exists  in  the  state  of  gas.  It 
forms  about  one-fifth  of  the  bulk  of  the  air  we  breathe,  and  is 
the  substance  which,  in  the  air,  supports  all  animal  life,  ail^  the 
combustion  of  all  burning  bodies.  It  is  necessary  also  to  the 
growth  of  plants,  so  that  were  it  by  any  cause  suddenly  re- 
moved from  the  atmosphere  of  our  globe,  every  living  thing  would 
perish,  and  all  combustion  would  become  impossible. 

6.  Nitrogen. — This  gas  is  very  easily  prepared.  Dissolve  a 
little  green  copperas  in  water,  and  pour  the  solution  into  a  flask, 
or  crystal  bottle,  provided  with  a  good  cork.  Add  a  little  of 
the  hartshorn  of  the  shops  (liquid  ammonia)  till  it  is  quite  muddy, 
put  in  the  cork  tight,  and  shake  the  bottle  well  for  five  minutes. 
Loosen  the  cork  well  without  removing  it,  so  as  to  allow  air  to 
enter  the  bottle.  Cork  tight  again  and  shake  as  before.  Re- 
peat this  as  often  as  the  loosening  of  the  cork  appears  to  admit 
any  air,  and  after  finally  shaking  it,  allow  it  to  stand  for  a  few 
minutes.     The  air  now  in  the  bottle  is  nearly  pure  nitrogen  gas. 

If  a  lighted  taper  be  introduced  into  the  bottle  it  will  be 
extinguished  by  this  gas,  but  no  other  effect  will  follow.  The 
gas  itself  does  not  take  fire  as  hydrogen  does.  Or  if  a  living 
animal  be  introduced  into  it,  breathing  will  instantly  cease,  and 
it  will  drop  without  signs  of  life. 


COMPOSITION    OF   THE    ORGANIC   PART   OF   PLANTS.  13 

This  gas  possesses  no  other  remarkable  property.  It  is  a 
very  little  lighter  than  common  air,  (as  9*71  to  100,)  and  exists 
in  large  quantity  in  an  micombined  state  in  the  atmosphere 
only.  Of  the  air  we  breathe  it  forms  nearly  four-fifths  of  the 
entire  bulk — the  remainder  being  oxygen.  In  the  process 
above  described  for  preparing  the  gas,  the  oxygen  is  absorbed 
by  the  iron,  and  the  nitrogen  left  behind. 

These  three  gases  are  incapable  of  being  distinguished  from 
common  air,  or  from  each  other  by  the  ordinary  senses  ;  but  by 
the  aid  of  the  taper  they  are  readily  recognised.  Hydrogen 
extinguishes  the  taper,  but  itself  takes  fire  ;  nitrogen  simply 
extinguishes  it  ;  while  in  oxygen  the  taper  burns  rapidly  and 
with  extraordinary  brilliancy. 

SECTION   V. PROPORTIONS      OF     THESE     ELEMENTARY     SUBSTANCES 

CONTAINED    IN   THE    ORGANIC    PART    OF    PLANTS   AND   ANIMALS. 

Of  the  one  solid  substance,  carbon,  and  the  three  gases,  hy- 
drogen, oxygen,  and  nitrogen,  above  described,  the  organic 
part  of  all  vegetable  and  animal  bodies  is  essentially  made  up. 
In  those  organic  substances  which  contain  nitrogen,  sulphur 
and  phosphorus  also  are  present,  but  generally  in  mmute  pro- 
portion. 

But  the  organic  part  of  plants  contains  these  four  substan- 
ces in  very  different  proportions.  Thus,  of  all  the  vegetable 
productions  which  are  gathered  as  food  by  man  or  beast,  in 
their  dry  state,  the 

Carbon  forms  nearly  one-half  by  weight, 
Oxygen  rather  more  than  one-third, 
Hydrogen  little  more  than  5  per  cent 
Nitrogen  from  ^  to  4  per  cent. 
Sulphur  1  to  5  per  cent, 
Phosphorus  about  a  thousandth  part. 

This  is  shown  in  part  by  the  following  table,  which  exhibits 


14  COMPOSITION    OF   THE    ORGANIC   PART   OF   PLANTS. 

the  actual  composition  of  1000  lb.  of  some  varieties  of  the  more 
common  crops,  when  made  ferfectly  dry : — 


Carbon. 

Hydrogen. 

Oxygen. 

Nitrogen. 

Ash. 

Hay, 

458  lb, 

50  lb. 

387  lb. 

15  1b. 

90  1b. 

Red  Clover  Hay, 

474 

50 

378 

21 

77 

Potatoes,    . 

440 

58 

447 

15 

40 

Wheat,      . 

461 

58 

434 

23 

24 

Wheat  Straw 

484 

63 

389J 

3J 

70 

Oats, 

507 

64 

367 

22 

4d 

Oat  Straw, 

501 

54 

390 

4 

51 

It  is  to  be  observed,  however,  that  in  drying  by  a  gentle 
heat,  1000  lb.  of  common  hay  from  the  stack  lost  158  lb.  of 
water;  of  clover  hay,  210  lb.;  of  potatoes  wiped  dry  externally, 
159  lb.  ;*  of  wheat,  145  lb.  ;  of  wheat  straw,  260  lb.  ;  of  oats, 
151  lb.  ;  and  of  oat  straw,  28 1  lb.  The  above  table  represents 
their  composition  when  thus  made  perfectly  dry. 

The  bodies  of  animals  contain  also  a  large   proportion  of 
water  ;  but  the  dry  matter  of  their  bodies,  as  a  whole,  is  dis- 
tinguished from  that  of  plants,  by  containing  a  larger  proportion 
of  nitrogen,   sulphur,   and  phosphorus.      Some   parts  of  the 
bodies  of   animals    are  particularly  rich  in  these  ingredients. 
Thus- 
Dry  lean  musde  contains  12  to  14  per  cent  of  nitrogen, 
Dry  hair  or  wool  about  5  per  cent  of  sulphur  ;  and 
Dry  lone  about  6  per  cent  of  phosphorus. 
But  in  animals,  as  in  plants,  the  chief  constituents  are  carboR 
and  oxygen.     Thus,  lean  beef,  blood,  white  of  egg,  and  the 
curd  of  milk,  when  quite  dry,  consist  in  100  parts  of  about — 

Per  cent. 
Carbon,  .....  55 

Hydrogen,  .....  7 

Nitrogen,  .  .  .  .  .  16 

Oxogen,  with  a  little  sulphur  and  phosphorus,  22 

100 

♦  Potatoes  contain  about  four-fifths  of  their  weight  of  water,  or  five  tons 
«f  roots  contain  nearly  four  tons  of  water.  Tumips  contain  sometimes  up» 
wards  of  ni-ne-tenths  of  their  weight  of  water. 


CHEMICAL   COMBINATION   AND   DECOMPOSITION.  15 


BECTICN   VI. OF    CHEMICAL     COMBINATION     AND    CHEMICAL    DECOM- 
POSITION. 

1°.  If  the  three  kinds  of  air  above  spoken  of  be  mixed  to- 
getlier  in  a  bottle,  no  change  will  take  place  ;  and  if  charcoal 
in  fine  powder  be  added  to  them,  still  no  new  substance  will  be 
produced.  Or  if  we  take  the  ash  left  by  a  known  weight  of  hay 
or  of  wheat  straw,  and  mix  it  with  the  proper  quantities  of  the 
four  elementary  substances — carbon,  hydrogen,  oxygen,  and 
nitrogen — as  shown  in  the  above  table,  we  shall  be  unable  by 
this  means  to  form  either  hay  or  wheat  straw.  The  elements 
of  which  vegetable  substances  consist,  therefore,  are  not  merely 
nixed  together,  they  are  united  in  some  closer  and  more  inti- 
mate manner.  To  this  more  intimate  state  of  union  the  term 
chemical  covibinaticn  is  applied — the  elements  are  said  to  be 
chemically  comlined. 

Thus,  when  charcoal  is  burned  in  the  air,  it  slowly  disappears, 
and  forms,  as  already  stated,  (p.  9,)  a  kind  of  air  known  by 
the  name  of  carbonic  acid  gas,  which  rises  into  the  atmosphere 
and  diffuses  itself  through  it.  Now  this  carbonic  acid  is  formed 
by  the  imion  of  the  carbon  (charcoal)  while  burning,  with  the 
oxygen  of  the  atmosphere,  and  in  this  new  air  the  two  elements, 
carbon  and  oxygen,  are  chemically  combined. 

Again,  if  hydrogen  be  burned  in  the  air  by  means  of  a  com- 
mon gas  jet,  (see  p.  24,)  water  is  formed,  and  the  hydrogen, 
and  a  portion  of  the  oxygen  of  the  atmosphere,  disappear  to- 
gether. The  two  gases  have  comlined  chemically  with  each  other, 
and  formed  water. 

2°.  On  the  other  hand,  if  a  piece  of  wood,  or  bit  of  straw, 
in  which  the  elements  are  already  chemically  combined,  be 
burned  in  the  air,  these  elements  are  separated,  and  made  to 
assume  new  states  of  combination,  in  which  new  states  they 
escape  into  the  air  and  become  invisible.  When  a  substance  is 
thus  changed,  and  converted  or  separated  into  other  substances 
by  the  action  of  heat,  or  in  any  other  way,  it  is  said  to  be  de- 


16  CHEMICAL   COMBINATION   AND   DECOMTOSITIOa. 

composed.  If  it  more  gradually  decay  and  perish,  as  animal  and 
vegetable  substances  do,  by  exposure  to  the  air  and  moisture, 
it  is  said  to  undergo  slow  decomposition. 

When,  therefore,  two  or  more  substances  unite  together,  so 
as  to  form  a  third,  possessing  properties  different  from  both,  they 
enter  into  chemical  union — they  form  a  chemical  combination,  or 
chemical  compound.  And  when,  on  the  other  hand,  a  compound 
body  is  so  changed  as  to  be  converted  into  two  or  more  sub- 
stances different  from  itself,  it  is  decomposed.  Thus  carbon, 
hydrogen,  and  oxygen  undergo  a  chemical  combination  in  the 
interior  of  the  plant  during  the  formation  of  wood — while  wood, 
again,  is  decomposed,  when  in  the  retort  of  the  vinegar-maker  it 
is  converted  among  other  substances  into  charcoal  and  wood- 
vinegar.  So  the  flour  of  grain  is  decomposed  when  the  brewer 
or  distiller  converts  it  into  ardent  spirits  ;  and  so  in  the  experi- 
ment described  in  section  iv,  for  preparing  oxygen  gas  from  red 
oxide  of  mercury,  the  oxide  is  decomposed  by  the  heat,  and  is 
resolved  into  its  two  constituent  elements,  oxygen  and  metallic 
mercury. 


CHAPTER  II. 

Form&  in  which  the  organic  elements,  carbon,  hydrogen,  oxygen,  nitrogen 
sulpnur,  and  phosphorus,  enter  into  plants. — Properties  of  the  carbonic, 
liumic,  ulmic,  geic,  and  crenic  acids,  and  of  humine  and  ulmine. — Of  water, 
and  its  relations  to  vegetable  life. — Of  ammonia,  its  properties  and  pro- 
duction in  nature. — Of  other  organic  alkalies  containing  nitrogen. — Of 
nitric  acid,  and  its  production  in  the  air  and  in  the  soil — Composition  of 
the  atmosphere. — Of  sulphuric  ^nd  phosphoric  acids. 

SECTION    I. FOKMS    IN    WHICH    THE     ORGANIC     ELEMENTS,    CARBON, 

HYDROGEN,    OXYGEN,    NITROGEN,    &C.,    ENTER   INTO    PLANTS. 

It  is  from  their  food  that  plants  derive  the  carbon,  hydrogen, 
oxygen,  and  nitrogen,  as  well  as  the  sulphur  and  phosphorus,  of 
which  their  organic  part  consists.  This  food  enters  partly  by 
the  minute  pores  of  their  roots,  and  partly  by  those  w^hich  exist 
in  the  green  parts  of  the  leaf  and  of  the  young  twig.  The  roots 
bring  up  food  from  the  soil,  the  leaves  take  it  in  directly  from 
the  air. 

Now,  as  the  pores  in  the  roots  and  leaves  are  very  minute, 
carbon  (charcoal)  cannot  enter  them  in  a  solid  state  ;  and  as  it 
does  not  dissolve  in  water,  it  cannot,  in  the  state  of  simple  car- 
bon, be  any  part  of  the  food  of  plants.  The  same  is  true  of 
Bulphur  and  phosphorus.  Again,  hydrogen  gas  neither  exists  in 
the  air  nor  usually  in  the  soil ;  so  that,  although  hydrogen  is 
always  found  in  the  substance  of  plants,  it  does  not  enter  them 
in  the  state  of  gas.  Oxygen,  on  the  other  hand,  exists  in  the 
air,  and  is  directly  absorbed  both  by  the  leaves  and  by  the  roots 
of  plants ;  whilQ  nitrogen,  though  it  forms  a  large  part  of  the 
atmosphere,  is  not  known  to  enter  directly  into  plants  in  any 
considerable  quantity. 

The  wfiole  of  the  carbon  and  hydrogen,  therefore,  and  tho 


18 


PROPERTIES   OF   CARBONIC   ACID. 


greater  part  of  the  oxygen  and  nitrogen  also,  enter  into  plants 
in  a  state  of  chemical  combinaticn  with  other  substances.  The 
carbon  is  taken  up  chiefly  in  the  state  of  carbonic  acid,  and  of 
certain  other  soluble  compounds  which  exist  in  the  soil;  the 
hydrogen  and  oxygen  in  the  form  of  water;  the  nitrogen  chiefly, 
it  is  supposed,  in  those  of  ammonia,  of  certain  other  soluble  sub- 
stances containing  nitrogen,  and  of  nitric  acid ;  and  the  sulphur 
and  phosphorus  in  those  of  sulphuric  and  phosphoric  acids.  It 
will  be  necessary,  therefore,  briefly  to  describe  these  several 
compounds. 

SECTION   II. OF   THE   CARBONIC,    HUMIC,    ULMIC,    GEIC,   AND 

CRENIC   ACIDS. 


1.  Carbonic  Acid. — If  a  few  pieces  of  chalk  or  lime-stone, 
Pig.  6. 


or  of  common  soda,  be  put  into  the  bottom  of  a  tumbler,  and  a 
little  spirit  of  salt  (muriatic  acid)  be  poured  upon  them,  a  boil- 
ing up  or  effervescence  will  take  place,  and  a  gas  will  be  given  oJQF, 
nrhich  will  gradually  collect  and  fill  the  tumbler;  and  when  pro- 
duced very  rapidly,  may  even  be  seen  to  run  over  its  edges. 


PROPERTIES    OF    CARBONIC    ACID. 


19 


This  gas  is  carbonic  acid.  It  cannot  be  distinguished  from 
common  air  by  the  eye;  but  if  a  lighted  taper  be  plunged  into 
it,  the  flame  will  immediately  be  extinguished,  while  the  gas 


will  remain  unchanged.  This  kind  of  air  is  so  heavy,  that  it 
may  be  poured  from  one  vessel  into  another,  and  its  presence  in 
the  second  vessel  recognised  as  before  by  the  use  of  the  taper. 
Or  it  may  be  poured  upon  a  lighted  candle,  which  it  will  in- 
stantly extinguish,  (fig.  6.)  This  gas  has  also  a  peculiar  odor, 
and  is  exceedi?igly  suffocating,  so  that  if  a  living  animal  be  in- 
troduced into  it,  life  immediately  ceases.  It  is  absorbed  by 
water — a  pint  of  water  absorbing  or  dissolving  a  pint  of  the  gas, 
and  acquiring  a  faintly  acid  taste. 

This  gas  derives  its  name  of  acid  from  this  taste,  which  it 
imparts  to  water,  and  from  its  property  of  reddening  vegetable 
blue  colors,  and  of  combining  with  alkaline*  substances  to  form 
carbonates.  The  former  property  may  be  shown  by  passing  a 
stream  of  the  gas  through  a  decoction  of  red  cabbage — as  in 

*  Acids  have  generally  a  sour  taste  like  vinegar,  and  redden  vegetable  blue?. 
Alkalinos,  again,  have  a  peculiar  taste  called  alkaline,  of  which  the  taste  of 
common  soda  or  of  hartshorn  are  examples ;  they  restore  the  blue  color  to 
vegetable  blues  which  have  been  reddened  by  an  acid,  and  they  unite  with 
acids  to  form  chemical  eombinations,  known  by  tlje  name  of  salts  or  salixv* 
lombin&tions. 


PROPERTIES   OP   CARBONIC  ACID. 


8 — when  the  liquid  will  gradually  become  red;  the  latter,  bj 
putting  lime  water  into  the  glass  instead  of  the  decoction  of  red 
cabbage,  when  the  stream  of  gas  will  render  it  milky,  forming 
carbonate  of  lime. 

Fig.  8. 


Carbonic  acid  gas  exists  in  the  atmosphere  ;  it  is  given  off 
from  the  lungs  of  all  living  animals  while  they  breathe  ;  it  is 
also  produced  largely  during  the  burning  of  wood,  of  coal,  and 
of  all  other  combustible  bodies,  so  that  an  unceasing  supply  of 
it  is  perpetually  being  poured  into  the  air.  Decaying  animal 
and  vegetable  substances  also  give  off  this  gas,  and  hence  it  is 
always  present  in  greater  or  less  abundance  in  the  soil,  and  es- 
pecially in  such  soils  as  are  rich  in  vegetable  matter.  It  is  pro- 
duced during  the  fermentation  of  malt  liquors,  or  of  the  ex- 
pressed juices  of  different  fruits,  such  as  the  apple,  the  pear,  the 
grape,  or  the  gooseberry — and  the  briskness  of  such  fermented 
liquors  is  due  to  the  escape  of  carbonic  acid  gas.  From  fer- 
menting dung  and  compost  heaps  it  is  also  given  off  ;  and  when 
put  into  the  ground,  farm-yard  manure  imparts  much  carbonic 
acid  to  the  soil  and  to  the  roots  of  plants. 

Carbonic  acid  consists  of  carbon  and  oxygen  only,  combined 
together  in  the  proportion  of  28  of  the  former  to  72  of  the  lat- 
ter. Or  100  lb.  of  carbonic  acid  contain  28  lb.  of  carbon  and 
12  lb.  of  oxygen. 

It  combines  with  potash,  soda,  lime,  magnesia,  ammonia,  &e 
forming  carbonates  oi  these  bases. 


HUMIC   AND   ULMIO   ACIDS.  21 

2.  Husric  AND  UlmIc  Acids. — ^The  soil  always  contains  a 
portion  of  decaying  vegetable  matter,  (called  humus  by  some 
writers, )  and  such  matter  is  always  added  to  it  when  it  is  ma- 
nured from  the  farm-yard  or  the  compost  heap.  During  the  de- 
cay of  this  vegetable  matter,  carbonic  acid,  as  above  stated,  is 
given  off  in  large  quantity,  but  other  substances  are  also  formed 
at  the  same  time.  Among  these  are  the  two  to  which  the 
names  of  huviic  and  ulmic  acids  are  respectively  given.  Both  of 
these  acids  contain  much  carbon, — they  are  both  capable  of  en- 
tering the  roots  of  plants,  and  both,  in  favorable  circumstances, 
help  to  feed  the  plant. 

In  peat  bogs  two  distinct  kinds  of  turf  are  frequently  recog- 
nised— a  light,  porous,  brown-colored,  and  a  dense,  compact, 
black  variety.  The  former  abounds  in  reddish-brown  ulmic,  the 
latter  in  brownish-black  humic  acid.  These  acids  may  readily 
be  extracted  from  the  peat  by  means  of  potash,  soda,  or  ammo- 
nia, in  solutions  of  which  they  easily  dissolve. 

Thus  if  the  common  soda  of  the  shops  be  dissolved  in  water, 
and  a  portion  of  a  rich  vegetable  soil,  or  a  bit  of  peat,  be  put 
into  this  solution,  and  the  whole  then  boiled,  a  brown  liquid  is 
obtained.  If  to  this  brown  liquid,  spirit  of  salt  (muriatic  acid) 
or  vinegar  be  added  till  it  is  sour  to  the  taste,  a  brown  flocky 
tasteless  powder  falls  to  the  bottom.  This  brown  substance  is 
humic  or  ulmic  or  geic  acid,  or  a  mixture  of  all  the  three.  In 
our  cultivated  soils,  the  humic  is  more  abundant  than  the  ulmic 
acid. 

The  quantity  of  these  mixed  acids,  extracted  in  this  way  from 
three  rich  soils,  was  respectively  4  J,  5  J,  and  8^  per  cent.  In 
most  of  our  arable  soils,  however,  the  proportion  present  is  con- 
siderably less. 

3.  Geic  Acid. — The  geic  acid  resembles  the  above  acids  in 
appearance,  but  contains  more  oxygen.  Like  them  it  exists  in 
the  soil  in  variable  quantity,  and  may  be  extracted  from  it  by 
solutions  of  potash,  soda,  or  ammonia,  and  is  thrown  down  from 
these  solutions  by  the  addition  of  an  acid. 


W  PROPERTIES   OF   CREKIC   AND   APOCRENIC   ACIDS. 

These  three  acids  have  so  strong  a  tendency  to  combine  with 
ammonia,  that  it  is  almost  impossible  to  obtain  them  free  from 
this  substance.  In  the  soil  they  absorb  it  whenever  it  is  pre- 
sent, and  if  exposed  to  the  air  in  a  moist  state,  they  drink  it  in 
from  the  atmosphere,  if  any  happen  to  be  floating  in  their  neigh- 
borhood. Hence  the  utility  of  partially  dried  peat  for  absorb- 
ing liquid  manure,  or  for  mixing  with  or  covering  fermenting 
compost  heaps. 

All  the  three  acids  above  named  are  sparingly  soluble  in  wa- 
ter, and,  therefore,  in  their  uncorabined  state  can  afford  little 
direct  nourishment  to  plants.  They  form  compounds  with  lime, 
magnesia,  and  oxide  of  iron,  which  are  also  very  sparingly  solu- 
ble, and  enter  little  into  the  roots  of  plants.  They  all  dissolve 
readily,  however,  when  they  are  combined  with  potash,  soda,  or 
ammonia.  And  as  the  latter  substance  especially  is  produced, 
and  is  always  present  in  the  soil,  and  as  these  acids  attract  it 
very  strongly,  there  is  good  reason  for  believing  that  they  are 
frequently  rendered  soluble  by  it,  and  that  in  this  way  ulmic, 
humic,  and  geic  acids  contribute  directly  to  the  nourishment  of 
our  cultivated  crops. 

4.  Crenic  and  Apocrenic  Acids. — By  these  names  are  dis- 
tinguished two  other  acid  substances  which  exist  in  the  soil,  and 
in  a  greater  degree,  perhaps,  and  more  directly,  promote  the 
growth  of  plants.  They  exist  in  the  water  of  all  bogs  and  mo- 
rasses, and  are  often  met  with  in  considerable  quantity  in  the 
water  of  springs,  especially  in  such  as  form  an  ochrey  deposit 
when  exposed  to  the  air.  They  are  produced  from  the  humic 
and  ulmic  acids  by  the  absorption  of  more  oxygen  from  the  at- 
mosphere, and,  like  them,  eagerly  combine  with  ammonia  ;  but 
they  are  lighter  in  color,  and  much  more  soluble  in  water. 

When  rich  soil  is  boiled  in  carbonate  of  soda,  as  above  de- 
scribed, and  the  humic,  ulmic,  and  geic  acids  are  thrown  down 
by  the  addition  of  muriatic  acid,  the  crenic  and  apocrenic  acids 
remain  still  in  the  solution,  and  may  be  separated  by  furthb* 
processes  which  it  is  unnecessary  here  to  describe. 


GENERAL   OBSERVATIONS.  23 

All  the  above  acids,  and  especially  the  two  latter,  exist  in 
greater  or  less  quantity  in  the  rich  brown  liquor  of  the  farm- 
yard, which  is  so  often  allowed  to  run  to  waste.  They  are  pro- 
duced, also,  during  the  decay  of  the  mixed  animal  and  vegeta- 
ble manure  we  add  to  the  soil,  and  yield  to  the  plant  a  portion 
of  that  supply  of  organic  food  which  it  must  necessarily  receive 
from  the  soil. 

5.  HuMixE  AND  Ulmixe  are  the  names  given  to  certain  inso- 
luble black  substances  formed  in  the  soil  along  with  the  humic 
and  other  acids  during  the  decay  of  vegetable  matter.  One  of 
the  ways  in  which  lime  acts  beneficially  upon  the  soil  is  supposed 
to  be  by  disposing  these  insoluble  matters  to  enter  into  new 
states  of  combination,  in  which  they  may  become  soluble,  and 
thus  capable  of  entering  into  the  roots  of  plants.* 

Of  the  important  substances  above  described,  I  may  further 
remark — 

a.  That  the  ulmic  acid  is  the  first  formed  from  the  decay  of 
vegetable  matter.  Hence,  in  peat  bogs  the  red  turf  is  usually 
found  nearest  to  the  surface. 

b.  That  the  humid  acid  is  formed  from  the  ulmic  by  the  ab 
sorption  of  more  oxygen  from  the  atmosphere.  It  consists  of 
carbon  and  water  only.     (See  page  50.) 

c.  That  the  geic  contains  more  oxygen  than  the  humic  acid, 
and  is  formed  from  it  by  the  absorption  of  a  further  quantity  of 
oxygen  from  the  air,  or  from  the  water  with  which  it  is  in  cg»l 
tact. 

d.  That  the  crenic  and  apocrenic  acids  contain  still  more  oxy- 
gen, and,  along  with  other  substances  produced  in  the  soil,  are 
formed  by  the  union  of  the  geic  acid  with  another  proportion  of 
oxygen. 

Thus  decaying  vegetable  matter  appears  first  to  form  the  ul- 
mic, next  the  humic,  than  the  geic,  after  that  the  crenic  and 
apocrenic  acids.     We  do  not  know  how  many  other  compounds 

*  See  in  the  Chapter  "  On  the  Use  of  Lime, "  the  sections  which  treat  ol 
the  chemioal  action  of  lime  when  applied  to  the  soil 


n 


COMPOSITION    OF    WATER. 


may  succeed  to  these  by  the  union  of  their  elements  with  more 
^nd  more  oxygen,  before  they  are  entirely  resolved  into  car- 
'lonic  acid, — the  final  state  to  which  all  these  changes  ultimately 
lead. 

These  excessive  absorptions  of  oxygen  by  the  decaying  veg- 
etable matter,  promote  the  production  of  ammonia  in  the  soil, 
as  well  as  of  nitric  acid.  This  fact  will  be  more  clearly  ex- 
plained in  section  vi. 

SECTION   III, OF     WATER,    ITS     COMPOSITION,     AND    ITS     RELATIONS 

TO   VEGETABLE    LIFE. 


If  hydrogen  be  prepared  in  a  bottle  in  the  way  already  de- 
ficribed,  (p.  9,)  and  a  gas-burner  be  fixed  into  its  mouth,  the 

Fig.  9. 


f 

f 

1 

■1 

hydrogen  may  be  lighted,  and  will  burn  as  it  escapes  into  the 
air,  (fig.  9.)  Held  over  this  flame,  a  cold  tumbler  will  become 
covered  with  dew,  or  with  little  drops  of  water.  This  water  is 
produced  during  the  burning  of  the  hydrogen  ;  and  as  its  pro- 
duction takes  place  in  pure  oxygen  gas  as  well  as  in  the  open 


SOLVENT  POWER  OF  WATER.  25 

air,  which  contains  oxygen — a  portion  of  the  oxygen  and  hydro- 
gen alone  disappearing — the  water  formed  must  contain  the 
hydrogen  and  oxygen  which  disappear,  or  must  consist  of  hydro- 
gen and  oxygen  only. 

This  is  a  very  interesting  fact ;  and  were  it  not  that  chemists 
are  now  familiar  with  many  such,  it  could  not  fail  to  appear 
truly  wonderful  that  the  two  gases,  oxygen  and  hydrogen,  by 
uniting  together,  should  form  water — a  substance  so  very  dif- 
ferent in  its  properties  from  either.  Water  consists  of  1  of 
hydrogen  united  to  8  of  oxygen  by  weight ;  or  every  9  lb.  of 
water  contain  8  lb.  of  oxygen  and  1  lb.  of  hydrogen. 

Water  is  so  familiar  a  substance  that  it  is  unnecessary  to 
dwell  upon  its  properties.  When  pure,  it  has  neither  color, 
taste,  nor  smell.  At  32°  of  Fahrenheit's  scale,  (the  freezing 
point,)  it  solidifies  into  ice  ;  and  at  212*^  it  boils,  and  is  con- 
verted into  steam.  It  possesses  two  other  properties,  which  are 
especially  interesting  in  connection  with  the  growth  of  plants. 

l5^.  If  sugar  or  salt  be  put  into  water,  they  disappear,  or  are 
dissolved.  Water  has  the  power  of  thus  dissolving  numerous 
other  substances  in  greater  or  less  quantity.  Hence,  when  the 
rain  falls  and  sinks  into  the  soil,  it  dissolves  a  portion  of  the 
soluble  substances  it  meets  with  in  its  way,  both  through  the 
air  and  through  the  soil,  and  rarely  reaches  the  roots  of  plants 
in  a  pure  state.  So  waters  that  rise  up  in  springs  are  rarely 
pure.  They  always  contain  earthy  and  saline  substances  in 
solution,  and  these  they  carry  with  them  when  they  are  sucked 
in  by  the  roots  of  plants. 

It  has  been  above  stated,  that  water  absorbs  (dissolves)  its 
own  bulk  of  carbonic  acid  ;  it  dissolves  also  smaller  quantities 
of  the  oxygen  and  nitrogen  of  the  atmosphere  ;  and  hence, 
when  it  meets  any  of  these  gases  in  the  soil,  it  becomes  im- 
pregnated with  them,  and  conveys  them  into  the  plant,  there  to 
serve  as  a  portion  as  its  food. 

In  nature,  water  never  occurs  in  a  pure  state.  It  generally 
contains  both  gaseous  and  saline  substances  in  a  state  of  solu- 
2 


26  PROPERTIES   or   AM5I0NIA. 

tion  ;  and  this,  no  doubt,  is  a  wise  provision  by  which  the  food 
of  plants  is  constantly  renewed  and  brought  within  their  reach. 

2d.  Water,  as  we  have  shown  above,  is  composed  of  oxygen 
and  hydrogen,  and  by  certain  chemical  processes  it  can  readily 
be  resolved  or  decomposed  artificially  into  these  two  gases.  The 
same  thing  takes  place  naturally  in  the  interior  of  the  living 
plant.  The  roots  and  leaves  absorb  the  water;  but  if  in  any  part 
of  the  plant  hydrogen  be  required  for  the  formation  of  the  sub- 
stance which  it  is  the  function  of  that  part  to  produce,  a  portion 
of  the  water  of  the  sap  is  decomposed  either  directly  or  indi- 
rectly, and  its  hydrogen  worked  up,  while  its  oxygen  is  set  free, 
or  converted  to  some  other  use.  So,  also,  where  oxygen  is 
required,  and  cannot  be  obtained  from  some  more  ready  source, 
water  is  decomposed,  the  oxygen  made  use  of,  and  the  hydrogen 
liberated.  Water,  therefore,  which  abound^  in  the  vessels  of 
all  growing  plants,  if  not  directly  converted  into  the  substance 
of  the  plant,  is  yet  a  ready  and  ample  source  from  which  a  sup- 
ply of  either  of  th?  elements  of  which  it  consists  may  at  any 
time  be  obtained. 

It  is  a  beautiful  adaptation  of  the  properties  of  this  all-perva- 
ding compound — water — that  its  elements  should  be  so  fixedly 
bound  together  as  rarely  to  separate  in  external  nature,  and  yet 
to  be  thus  at  the  command  and  easy  disposal  of  the  vital  pow- 
ers of  the  humblest  order  of  living  plants. 

SECTION     IV. OF    AMMONIA,    ITS    PROPERTIES    AND    PRODUCTION    IN 

NATURE. 

If  the  sal-ammoniac,  or  the  sulphate  of  ammonia  of  the  shops, 
be  mixed  with  quick-lime,  a  powerful  odor  is  immediately  per- 
ceived, and  an  invisible  gas  is  given  oflf,  which  strongly  affects 
the  eyes.  This  gas  is  ammonia.  Water  dissolves  or  absorbs 
it  in  very  large  quantity,  and  this  solution  of  the  gas  in  water 
fonus  the  common  hartshorn  of  the  shops.    The  white  solid 


NATURAL   PRODUCTION    OF   AMMONIA.        '  21 

Bmelling-salts  of  the  shops  (carbonate  of  ammonia)  are  a  com- 
pound of  ammonia  with  carbonic  acid  and  a  little  water. 

Ammonia  consists  of  nitrogen  and  hydrogen  only,  in  the  pro- 
portion of  14  of  the  former  to  3  of  the  latter  by  weight ;  or  17 
lb.  of  ammonia  contain  14  lb.  of  nitrogen  and  3  lb.  of  hydrogen. 

The  decay  of  animal  substances  is  an  important  natural 
source  of  this  compound.  During  the  putrefaction  of  dead  ani- 
mal bodies,  ammonia  is  invariably  given  off.  From  the  animal 
substances  of  the  farm-yard  it  is  evolved  during  their  decay  or 
putrefaction,  as  well  as  from  all  solid  and  liquid  manures  of  ani- 
mal origin. 

Ammonia  is  naturally  formed,  also,  during  the  decay  of  veg- 
etable substances  in  the  soil.  This  happens  in  one  or  other  of 
three  ways. 

a.  As  in  animal  bodies,  by  the  direct  union  of  the  nitrogen 
with  a  portion  of  the  hydrogen  of  which  they  consist. 

h.  Or  by  the  combination  of  a  portion  of  the  hydrogen  of  the 
decaying  plants  with  the  nitrogen  of  the  air. 

c.  Or  when  they  decompose  in  contact,  at  the  same  time, 
with  both  air  and  water — by  their  taking  the  oxygen  of  a 
quantity  of  the  water,  and  disposing  its  hydrogen  at  the  mo- 
ment of  liberation,  to  combine  with  the  nitrogen  of  the  air,  and 
form  ammonia. 

The  production  of  ammonia  by  either  of  the  two  latter 
modes,  takes  place  most  abundantly  when  the  oxygen  of  the  air 
does  not  gain  very  ready  access.  Such  are  open  subsoils  in 
which  vegetable  matter  abounds.  And  thus  one  of  the  benefits 
which  follow  from  thorough  draining  and  subsoil  ploughing  is, 
that  the  roots  penetrate  and  fill  the  subsoil  with  vegetable  mat- 
ter, which,  by  its  decay  in  the  confined  atmosphere  of  the  sub- 
soil, gives  rise  to  this  production  of  ammonia.  When  thus 
formed  in  the  soil,  it  is  at  once  absorbed  and  retained  by  the 
humic  and  ulmic  acids  already  described,  renders  them  soluble, 
and  enters  with  them  into  the  roots  of  living  plants. 

Ammonia  is    also   formed    naturally  during  the    chemical 


tt  OTHER   ORGANIC    ALKALIES. 

changes  that  are  produced  in  volcanic  countries,  through  the 
agency  of  subterranean  fires.  It  escapes  often  in  considerable 
quantities  from  the  hot  lavas,  and  from  crevices  in  the  heated 
rocks. 

It  is  produced  artificially  by  the  distillation  of  animal  sub- 
stances, (hoofs,  horns,  &c.,)  and  during  the  burning,  coking, 
and  distillation  of  coal.  Soot  contains  much  ammonia,  while 
thousands  of  tons  of  that  which  is  present  in  the  ammoniacal 
liquors  of  the  gas-works,  and  which  might  be  beneficially  applied 
as  a  manure,  are  annually  carried  down  by  the  rivers,  and  lost 
in  the  sea. 

Of  the  ammonia  which  is  given  off  during  the  putrefaction  of 
animal  and  vegetable  substances,  a  variable  proportion  rises 
into  the  air,  and  floats  in  the  atmosphere,  till  it  is  either  decom- 
posed by  natural  causes,  or  is  dissolved  and  washed  down  by 
the  rains.  In  the  latter  case  it  sinks  into  the  ground,  and  finds 
its  way  into  the  roots  of  plants.  In  our  climate,  cultivated 
plants  appear  to  derive  a  considerable  proportion  of  their  nitro- 
gen from  ammonia.  It  is  one  of  the  most  valuable  fertilizing 
substances  contained  in  farm-yard  manure  ;  and  as  it  is  usually 
present  in  greater  proportion  in  the  liquid  than  in  the  solid  con- 
tents of  the  farm-yard,  much  real  wealth  is  lost,  and  the  means 
of  raising  increased  crops  thrown  away,  in  the  quantities  of 
liquid  manure  which  are  almost  everywhere  permitted  to  ran 
to  waste. 

SECTION   V. OF  OTHER  ORGANIC   ALKALIES,   AND   THEIR  INFLUENCK 

UPON   VEGETATION. 

Ammonia  has  hitherto  been  considered  by  chemists  as  the 
only  organic  substance  of  a  volatile  and  alkaline  nature,  which 
exercised  a  sensible  influence  upon  vegetation.  But  a  number 
of  other  organic  alkalies,  volatile  like  ammonia,  possessed  of  a 
powerful  odor,  soluble  in  water,  and  like  it  containing  nitrogen^ 
have  recently  been  discovered.     Some  of  these  are  of  such  a  kind 


NITRIC  ACID.  2ft 

B8  to  be  naturally  produced,  I  believe,  during  the  decay  and 
fermentation  of  animal  and  vegetable  substances  ;  and  if  so, 
they  cannot  fail  to  affect  the  growth  of  plants. 

These  alkaline  compounds  contain  carbon  in  addition  to  the 
hydrogen  and  nitrogen  of  which  ammonia  consists.  Hence  if 
they  exist,  or  are  formed  in  the  soil,  they  will  be  able  to  minis- 
ter these  three  elements  to  the  wants  of  the  plant,  and  in  a  form 
of  combination  in  which  they  may  be  more  readily  converted 
into  those  substances  of  which  the  parts  of  the  plant  are  com- 
posed. 

No  experiments  have  yet  been  made  upon  the  relations  which 
these  compounds  bear  to  vegetable  life,  to  fertility  of  soil,  or  to 
fertilizing  manures  ;  but  I  insert  these  brief  remarks  regarding 
them  in  this  place  from  the  persuasion,  that  the  study  of  these 
relations  will  afford  the  materials  for  an  intricate,  perhaps,  but 
most  interesting  and  important  chapter  in  future  histories  of  the 
phenomena  of  vegetation. 

SECTION  VI. OF   NITRIC   ACID,   AND    ITS   PRODUCTION   IN  THE   AIR 

AND   IN  THE   SOIL. 

Nitric  acid  is  a  powerfully  corrosive  liquid,  known  in  the  shops 
by  'the  familiar  name  of  aquafortis.  It  is  prepared  by  pouring 
oil  of  vitriol  (sulphuric  acid)  upon  saltpetre,  and  distilling  the 
mixture.  The  aquafortis  of  the  shops  is  a  mixture  of  the  pure 
acid  with  water. 

Pure  nitric  acid  consists  of  nitrogen  and  oxygen  only,  united 
in  the  proportions  of  14  of  nitrogen,  by  weight,  to  40  of  oxygen. 
It  is  very  remarkable  that  the  union  of  these  two  gases,  so 
harmless  in  the  air,  should  produce  the  burning  and  corrosive 
compound  which  this  acid  is  known  to  be. 

It  never  reaches  the  roots  or  leaves  of  plants  in  this  free  and 
corrosive  state.  It  exists  and  is  produced  in  many  soils,  and  is 
naturally  formed  in  compost  heaps,  and  in  most  situations  where 
animal  or  vegetable  matter  is  undergoing  decay  in  contact  with 


t#  PROPERTIES   OF   NITRIC   ACID. 

the  air  ;  but  in  these  cases  it  is  always  found  in  a  state  of  che- 
mical combination.  With  potash  it  forms  nitrate  of  -potash, 
(saltpetre,)  with  soda,  nitrate  of  soda,  with  lime,  nitrate  of  lime., 
with  magnesia,  nitrate  of  magnesia,  with  ammonia,  nitrate  of 
ammonia,  and  so  on.  All  these  nitrates  are  very  soluble  in  wa- 
ter, and  it  is  generally  in  the  state  of  one  or  other  of  these  com- 
pounds that  nitric  acid  exists  in  the  soil  and  reaches  the  roots 
of  plants. 

It  is  well  known  that  saltpetre — called  also  nitre,  or  nitrate 
of  potash — is  in  India  obtained  by  washing  the  rich  alluvial  soil 
of  certain  districts  with  water,  and  evaporating  the  clear  solu- 
tion to  dryness.  On  the  continent  of  Europe,  artificial  nitre- 
beds  are  formed  by  mixing  together  earthy  matters  of  various 
kinds  with  the  liquid  and  dung  of  stables,  and  forming  the  mix- 
ture into  heaps,  which  are  turned  over  once  or  twice  a  year. 
These  heaps,  on  washing,  yield  an  annual  crop  of  impure  salt- 
petre. The  soil  around  our  dwellings,  and  upon  which  our 
towns  and  villages  stand,  becomes  impregnated  with  animal  mat- 
ter of  various  kinds  through  defective  drainage,  and  is  thus  con- 
verted into  extensive  nitre-beds,  in  which  nitric  acid  and  nitrates 
are  produced  in  great  abundance.  The  rains  that  fall  and  sink 
into  the  soil  wash  these  downwards  into  the  wells,  if  any  are 
near.  Hence  nitrates  usually  abound  in  wells  which  are  dug 
within  the  walls  of  large  towns  ;  and  the  waters  of  such  wells 
are  generally  unwholesome  to  man,  though  they  would  wonder- 
fully nourish  plants,  if  employed  for  the  purposes  of  irrigation.* 

Nitric  acid  is  also  naturally  formed,  and  in  some  countries 

*  "  In  Leon  (Nicaragua)  the  practice  of  burying  in  the  churches  has  al- 
ways prevailed,  and  is  perpetuated  through  the  influence  of  the  priests,  wlio 
derive  a  considerable  fee  from  each  burial.  Tlie  consequence  is,  that  the 
ground  within  and  around  the  churches  has  become  (if  the  term  is  admissi- 
ble) saturated  with  the  dead.  Tlie  burials  are  made,  according  to  the  amount 
paid  to  the  Church,  for  from  ten  to  twenty-five  years,  at  the  end  of  which 
time  the  hones  with  the  earth  around  tJiem  are  removed  and  sold  to  the  »nani*« 
facturers  qf  nitre." — Squieb'S  Nicaragua,  vol  i.  p.  384. 


PRODUCTION    OF   NITRIC   ACID.  31 

probably  in  large  quantities,  by  the  passage  of  electricity  through 
the  atmosphere.  The  air  consists  of  oxygen  and  nitrogen  mixed 
together,  but  when  electric  sparks  are  passed  through  a  quan- 
tity of  air,  minute  portions  of  the  two  gases  unite  together  che- 
mically, so  that  every  spark  which  passes  forms  a  small  quantity 
of  nitric  acid.  A  flash  of  lightning  is  only  a  large  electric 
spark  ;  and  hence  every  flash  that  crosses  the  air  produces 
along  its  path  a  sensible  proportion  of  this  acid.  Where  thun- 
der-storms are  frequent,  much  nitric  acid,  and  probably  some 
ammonia,  are  produced  in  this  way  in  the  air.  They  are  washed 
down  by  the  rains — in  which  they  have  frequently  been  de- 
tected— and  thus  reach  the  soil,  where  the  acid  combines  with 
potash,  soda,  lime,  &c.,  and  produces  the  nitrates  above  men- 
tioned. 

It  has  long  been  observed  that  those  parts  of  India  are  the 
most  fertile  in  which  saltpetre  exists  in  the  soil  in  the  greatest 
abundance.  The  nitl*ates  of  soda  and  potash  have  been  found 
among  ourselves,  also,  wonderfully  to  promote  vegetation,  when 
artificially  applied  to  growing  crops  ;  and  it  is  a  matter  of  fre- 
quent remark,  that  vegetation  seems  to  be  refreshed  and  invigo- 
rated by  the  fall  of  a  thunder-shower.  There  is,  therefore,  no 
reason  to  doubt  that  nitric  acid  is  really  beneficial  to  the  gene- 
ral vegetation  of  the  globe.  And  since  vegetation  is  most  lux- 
uriant in  those  parts  of  the  globe  where  thunder  and  lightning 
are  most  abundant,  it  would  appear  as  if  the  natural  production 
of  this  compound  body  in  the  air,  to  be  afterwards  brought  to 
the  earth  by  the  rains,  were  a  wise  and  beneficent  contrivance 
by  which  the  health  and  vigor  of  universal  vegetation  is  in- 
tended to  be  promoted. 

It  is  from  nitric  acid,  thus  universally  produced  and  existing, 
that  plants  appear  to  derive  a  large — probably,  taking  the  vege- 
tation of  the  earth  as  a  whole,  the  largest — proportion  of  their 
nitrogen.  In  all  climates,  they  also  derive  a  portion  of  this 
element  from  ammonia,  and  from  other  soluble  compounds  con* 


t$  COMPOSITION    OF   THE   ATMOSPHERE. 

taining  nitrogen;  but  less,  probably,  from  these  sources  in  tropi- 
cal than  in  temperate  climates.* 

SECTION   VII.— OF   THE    COMPOSITION    OF   THE   ATMOSPHERE. 

The  air  we  breathe,  and  from  which  plants  derive  a  portion  of 
their  nourishment,  consists  of  a  mixture  of  oxygen  and  nitrogen 
gases,  with  a  minute  quantity  of  carbonic  acid,  and  a  variable 
proportion  of  watery  vapor.  Every  hundred  gallons  of  dry  air 
contain  about  21  gallons  of  oxygen  and  79  of  nitrogen.  The 
carbonic  acid  amounts  only  to  one  gallon  in  2500,  while  the 
watery  vapor  varies  from  one  to  two  and  a  half  gallons  (of 
steam)  in  100  gallons  of  common  air. 

The  oxygen  of  the  atmosphere  is  necessary  to  the  breathing 
of  animals,  to  the  life  of  plants,  and  to  the  burning  of  bodies 
in  the  air.  The  nitrogen  serves  principally  to  dilute  the  strength, 
so  to  speak,  of  the  pure  oxygen — in  which  gas,  if  unmixed, 
animals  would  live,  and  combustibles  burn  with  too  great  ra- 
pidity. The  small  proportion  of  carbonic  acid  in  the  atmo- 
sphere affords  an  important  part  of  their  food  to  plants,  and  the 
watery  vapor  iiids  in  keeping  the  surfaces  of  animals  and  plants 
in  a  moist  and  pliant  state,  rt^hile,  in  due  season,  it  descends 
also  in  refreshing  showers,  or  studs  the  evening  leaf  with  spark- 
ling dew. 

There  is  thus  in  thie  composition  of  the  atmosphere  a  beau- 
tiful adjustment  to  the  nature  and  necessities  of  living  beings. 
The  energy  of  the  pure  oxygen  is  tempered,  yet  not  too  much 
weakened,  by  the  admixture  of  nitrogen  gas.  The  carbonic 
acid,  which,  when  undiluted,  is  noxious,  especially  to  animal  life, 
is  mixed  with  the  other  gases  in  so  minute  a  proportion,  as  to 
be  harmless  to  animals,  while  it  is  still  beneficial  to  plants ;  and 
when  the  air  is  overloaded  with  watery  vapor,  it  is  provided 
that  it  shall  descend  in  rain. 

*  For  fuller  infonnation  on  tliis  point,  see  the  Author's  Lectures  ov  Agn 
eultural  Ohemistry  and  Geology^  2d  edition. 


SULPHURIC   AND   PHOSPHORIC   ACIDS.  3S 

But  the  air  contains  besides  many  other  substances  not  essen- 
tial to  its  composition,  but  which  exercise,  nevertheless,  an 
important  influence  both  upon  animal  and  vegetable  life.  We 
have  already  seen  that  nitric  acid,  and  probably  ammonia,  are 
produced  in  it  by  the  agency  of  electricity,  and  are  brought 
down  by  the  rains.  There  are  continually  rising  into  it  also 
vapors  and  exhalations  of  various  kinds  from  the  earth's  sur- 
face. The  sea  sends  up  a  portion  of  its  common  salt  and  other 
constituents,  and  the  land  the  numberless  forms  of  volatile 
matter  which  arise  from  decaying  animal  and  vegetable  sub- 
stances, from  festering  marshes,  from  burning  volcanoes,  and 
from  countless  manufactories  and  chemical  operations.  As  the 
ocean  receives  all  that  water  can  carry  into  it,  so  the  atmo- 
sphere receives  everything  that  'the  air  can  bear  up. 

And  lest  these  ever-rising  exhalations  should  contaminate  the 
aiTf  and  render  it  unfit  for  the  breathing  of  animals,  the  rains, 
as  they  descend,  dissolve,  wash  out,  and  bring  them  back  again 
to  the  soil.  Thus  they  purify  at  once,  the  atmosphere  through 
which  they  fall,  and  bear  refreshment  to  the  land,  and  the 
means  of  fertility,  wherever  they  come. 

SECTION   VIII. OF    SULPHURIC   AND    PHOSPHORIC    ACIDS. 

We  have  stated  in  a  previous  section  that  sulphuric  and  phos- 
phoric acids  are  the  chief  forms  in  which  sulphur  and  phospho- 
rus respectively  enter  into  plants. 

1°.  Sulphuric  Acid — known  also  as  oil  of  vitriol — ^is  a  very 
heavy,  oily-looking,  sour,  and  corrosive  liquid,  which  becomes 
hot  when  mixed  with  water,  chars  and  blackens  straw  or  wood 
when  immersed  in  it,  and  is  capable  of  dissolving  many  organic 
and  inorganic  substances.  It  is  manufactured  by  burning  sul- 
phur in  large  leaden  chambers,  and  consists  of  sulphur  and 
oxygen  only — combined  with  a  little  water.  One  pound  of 
sulphur  produces  about  three  pounds  of  the  strongest  sulphuric 
acid. 

2* 


84  SULPHURIC   AND   PHOSPHORIC   ACIDS. 

This  acid  combines  with  potash,  soda,  lime,  magnesia,  and 
ammonia,  and  forms  sulphates.  These  sulphates  exist  in  the  soil, 
fcnd  when  dissolved  by  water  are  conreyed  into  the  sap  of  plants, 
and  supply  the  sulphur  which  is  necessary  for  the  formation 
of  their  growing  parts. 

The  strong  acid  is  now  employed  largely  for  dissolving  bones 
and  the  fossil  phosphates  of  lime,  from  which  the  artificial  ma- 
nure known  as  super-phosphate  of  lime  is  manufactured.  In  a 
diluted  state  it  has  been  employed  with  advantage  as  a  steep 
for  barley,  and  even  as  a  manure  for  turnips. 

2°.  Phosphoric  Acid. — If  a  piece  of  phosphorus  be  kindled 
in  the  air,  it  burns  with  a  brilliant  flame,  and  gives  oflf  dense 
Thitc  fumes.  These  white  fumes  are  phosphoric  acid.  They 
are  produced  by  the  union  of  the  burning  phosphorus  with  the 
oxygen  of  the  atmosphere.  A  100  lb.  of  phosphorus,  when 
burned,  form  22 1^  lb.  of  phosphoric  acid. 
Fig.  10. 


If  the  experiment  be  performed  under  a  glass,  as  in  the 
annexed  figure,  the  white  fumes  of  acid  will  condense  on  the 
cool  inside  of  the  vessel  in  the  form  of  a  white  powder,  which 
speedily  absorbs  moisture  from  the  air,  and  runs  to  a  liquid. 
This  acid  is  very  sour  and  corrosive.  It  combines  with  potash, 
lime,  &c.,  and  forms  phosphates,  and  in  these  states  of  combina- 
tion it  exists  in  soils  and  manures,  and  enters  into  plants.  The 
bones  of  animals  contain  a  large  proportion  of  this  acid,  chiefly 
in  combination  with  lime  and  magnesia. 

Lucifer  matches  are  tipped  with  a  morsel  of  phosphorus, 
which,  when  rubbed,  takes  fire  and  kindles  the  sulphur.  The 
white  smoke  given  oflf  by  such  a  match,  when  first  kindled,  con- 
sists of  phosphoric  acid. 


CHAPTER  III. 

Structure  of  the  stem,  root,  and  leaves  of  plants. — Functions  of  the  root, 
the  leaves,  and  the  stem. — How  plants  draw  their  nourishment  from  tho 
soil  and  the  air. — Of  the  substance  of  plants,  and  the  structure  of  the 
seed  or  grain. — Of  cellulose,  starch,  sugar,  gum,  mucilage,  and  pectoso, 
or  pectic  acid. — Of  the  oil  or  fat,  wax,  resin,  and  turpentine  of  plants. — Of 
gluten,  albumen,  and  casein. — Germination  of  seeds  and  growth  of  plants. 
— Mutual  transformations  of  starch,  sugar,  and  cellulose. — Production  of 
cellular  fibre  from  the  organic  food  of  plants. — Necessity  of  nitrogen,  or 
Bubstances  containing  it,  to  the  growth  of  plants. — Forms  in  which  nitro- 
gen may  enter  into  plants. 

From  the  compound  substances  described  in  the  preceding 
chapter,  plants  derive  the  greater  portion  of  the  carbon,  hydro- 
gen, oxygen,  and  nitrogen,  with  the  sulphur  and  phosphorus  of 
which  their  organic  part  consists.  The  living  plant  possesses 
the  power  of  absorbing  these  compound  bodies,  of  decomposing 
them  in  the  interior  of  its  several  vessels,  and  of  re-compounding 
their  elements  in  a  different  way,  so  as  to*  produce  new  sub- 
stances,— the  ordinary  products  of  vegetable  life. 

Before  describing  the  nature  of  these  new  substances,  I  shall 
briefly  consider  the  general  structure  of  plants,  and  their  mode 
of  growth. 

SECTION  I. OF  THE  STRUCTURE  OP  THE  STEM,  ROOT,  AND  LEAVES 

OF  PLANTS. 

A  perfect  plap.t  consists  of  three  several  parts: — a  root  which 
throws  out  arms  and  fibres  in  all  directions  into  the  soil ;  a 
trunk  which  branches  into  the  atmosphere  on  every  side  ;  and 
leaves  which,  from  the  ends  of  the  branches  and  twigs,  spread 
out  a  more  or  less  extended  surface  into  the  surrounding  air. 


86      STRUCTURE  OF  THE  STEM  AND  ROOT  OF  PLANTS. 

Each  of  these  parts  has  a  peculiar  structure,  and  special  func- 
tions assigned  to  it. 

1°.  The  stem  of  any  of  our  common  trees  consists  of  three 
•  parts — the  pith  in  the  centre,  the  wood  surrounding  the  pith, 
and  the  bark  which  covers  the  whole.  The  pith  consists  of  a 
collection  of  minute  cells,  supposed  to  communicate  horizontally 
with  the  external  air  through  the  medullary  rays  and  the  outer 
bark  ;  while  the  wood  and  inner  bark  are  composed  of  long 
tubes  bound  together  in  a  vertical  position,  so  as  to  be  capable 
of  carrying  liquids  up  and  down  between  the  roots  and  the 
leaves.  When  a  piece  of  wood  is  sawn  across,  the  ends  of 
these  tubes  may  be  distinctly  seen.  The  branch  is  only  a  pro- 
longation of  the  stem,  and  has  a  similar  structure. 

2°.  The  root,  immediately  on  leaving  the  trunk  or  stem,  has 
also  a  similar  structure.  But  as  the  root  tapers  away,  the  pith 
disappears — in  some,  as  in  the  walnut  and  horse-chestnut,  grad- 
ually— in  others  immediately.  The  bark  also  thins  out,  and  the 
wood  softens,  till  the  white  tendrils,  of  which  its  extremities  arc 
composed,  consist  only  of  a  colorless  spongy  mass,  full  of  pores, 
and  in  which  no  distinction  of  parts  can  be  perceived.  In  this 
spongy  mass  the  vessels  or  tubes  which  descend  through  the 
stem  and  root  lose  themselves,  and  by  these  tubes  the  spongy 
extremities  in  the  sOil  are  connected  with  the  leaves  in  the  air. 

3°,  The  leaf  is  an  expansion  of  the  twig.  The  fibres,  which 
are  seen  to  branch  out  from  the  base  through  the  interior  of  the 
leaf,  are  prolongations  of  the  vessels  of  the  wood,  and  are  con- 
nected with  similar  prolongations  of  the  inner  bark,  which  usu- 
ally lie  beneath  them.  The  green  exterior  portion  of  the  leaf  is, 
in  like  manner,  a  continuation  of  the  outer  or  cellular  tissue  Ox 
the  bark,  in  a  very  thin  and  porous  form.  The  pores,  or  mouths, 
(stomata)  contained  in  the  green  part,  are  an  essential  feature 
in  the  structure  of  the  leaves,  and  are  very  numerous.  The 
leaf  of  the  common  lilac  contains  as  many  as  120,000  of  them 
on  a  square  inch  of  surface.  They  are  generally  most  numerous  . 
on  the  under  part  of  the  leaf,  but  in  the  case  of  leaves  which 
float  upon  water,  they  are  chiefly  confined  to  the  upper  part. 


FUNCTIONS   OF   THE   ROOT.  81 

The  annexed  woodcut  shows  the  appearance  of  the  oval  pores 
p  on  the  leaf  of  the  garden  balsam.  Connected  with  these 
pores,  the  green  part  of  the  leaf  consists  of  or  contains  a  collec- 

Fig.  11. 


tion  of  tubes  or  vessels  which  stretch  along  the  surface  of  the 
leaf,  and  communicate,  as  we  have  said,  with  those  of  the  inner 
bark. 

SECTION     II. FUNCTIONS     OF     THE    ROOT,     THE    LEAVES,    AND    THE 

STEM. COURSE    AND    MOTION    OF   THE    SAP. 

Each  of  these  principal  parts  of  the  plant  performs  its  pecu- 
liar functions. 

1°.  Functions  of  the  root. — The  root  sends  out  fibres  in  every 
direction  through  the  soil  in  search  of  water  and  of  liquid  food, 
which  its  spongy  extremities  suck  in,  and  send  forward  with  the 
sap  to  the  upper  parts  of  the  tree.  It  is  to  aid  the  roots  in 
procuring  the  food  more  rapidly  that  in  the  art  of  culture  such 
substances  are  mixed  with  the  soil  as  experience  has  shown  to 
be  favorable  to  the  growth  of  the  plants  we  wish  to  raise. 

What  chemical  changes  the  food  is  made  to  undergo  in  en- 
tering or  passing  along  the  roots  is  not  yet  understood. 

2°.  Functions  of  the  leaf— ;lt  is  not  so  obvious  to  the  common 
observer  that  the  leaves  spread  out  their  broad  surfaces  into  the 
air  for  the  same  purpose  precisely  as  that  for  which  the  roots 
diffuse  their  fibres  through  the  soil ;  the  only  difference  is,  that 
while  the  roots  suck  in  chiefly  liquid,  the  leaves  inhale  almost 


58  FUNCTIONS   OF   THE    LEAF. 

solely  gaseous  food.  In  the.  daytime,  whether  in  the  sv/nshine  or 
in  the  shade,  the  green  leaves  are  continually  absorbing  carbonic 
acid  from  the  air,  and  giving  off  oxygen  gas.  That  is  to  say, 
they  are  continually  appropriating  carbon  from  the  air.*  When 
night  comes,  this  process  is  reversed,  and  they  begin  to  absorb  oxygen 
and  to  give  off  carbonic  acid.  But  the  latter  process  does  not 
go  on  so  rapidly  as  the  former  ;  so  that,  on  the  whole,  plants, 
when  growing,  gain  a  large  portion  of  carbon  from  the  air. 
The  actual  quantity,  however,  varies  with  the  season,  with  the 
climate,  and  with  the  kind  of  plant.  The  proportion  of  its 
carbon,  which  has  been  derived  from  the  air,  is  greatly  modified, 
also,  by  the  quality  of  the  soil  in  which  the  plant  grows,  and 
by  the  comparative  abundance  of  liquid  food  which  happens  to 
be  within  reach  of  its  roots.  It  has  been  ascertained,  however, 
that  in  our  climate,  on  an  average,  not  less  than  from  one-third 
to  four-fifths  of  the  entire  quantity  of  carbon  contained  in  the 
crops  we  reap  from  land  of  average  fertility,  is  really  obtained 
from  the  air. 

We  see  then  why,  in  arctic  climates,  where  the  sun,  once  risen, 
never  sets  again  during  the  entire  summer,  vegetation  should 
almost  rush  up  from  the  frozen  soil ;  the  green  leaf  is  ever 
gaining  from  the  air  and  never  losing,  ever  taking  in  and  never 
giving  off  carbonic  acid,  since  no  darkness  ever  interrupts  or 
suspends  its  labors. 

How  beautiful,  too,  does  the  contrivance  of  the  expanded 
leaf  appear  !  The  air  contains  only  one  gallon  of  carbonic  acid 
in  2500,  and  this  proportion  has  been  adjusted  to  the  health 
and  comfort  of  animals  to  whom  this  gas  is  hurtful.  But  to 
catch  this  minute  quantity,  the  tree  hangs  out  thousands  of 
square  feet  of  leaf — in  perpetual  motion,  through  an  ever-moving 
air  ;  and  thus,  by  the  conjoined  labors  of  millions  of  pores,  the 
substance  of  whole  forests  of  solid  wood  is  slowly  extracted  from 
the  fleeting  winds.     I  have  already  mentioned  the  number  of 

*  Since  carbonic  acid,  as  shown  in  the  previous  chapter,  (p.  20,)  consists 
only  of  carbon  and  oxygen.  Of  these  the  leaves  retain  the  carbon  and  r^ 
ject  the  oxygen. 


SUBSTANCE   OF   PLANTS.  89 

pores  which  have  been  observed  on  a  square  inch  of  leaf  ;  and 
when  I  add  that  on  a  single  oak  tree  seven  millions  of  leaves 
have  been  counted,  the  multitude  of  absorbing  mouths  in  a  for- 
est— like  those  of  the  coralline  animals  in  a  reef — will  appear 
equal  to  the  most  gigantic  effects. 

The  green  stem  of  the  young  shoot,  and  the  green  stalks  of 
the  grasses,  also  abound  in  pores,  and  consequently  absorb  car- 
bonic acid,  and  give  off  oxygen,  as  the  green  leaf  does  ;  and 
thus  a  larger  supply  of  food  is  afforded  when  the  growth  is  most 
rapid,  or  when  the  short  life  of  the  annual  plant  demands  much 
nourishment  within  a  limited  time.  The  yellow  and  red  leaves 
and  parts  of  plants  give  off  no  oxygen,  (Senebier.) 

3°.  Functions  of  the  stem. — From  the  spongy  part  of  the  root 
the  sap  ascends  through  the  vessels  of  the  woody  stem  till  it  is 
diffused  over  the  interior  of  the  leaf  by  the  woody  fibres  which 
the  leaf  contains.  During  this  passage  the  substances  which  the 
sap  contains  undergo  certain  chemical  changes,  which  are  as  yet 
not  well  understood.  From  the  woody  fibre  of  the  leaf — along 
the  vessels  which  lie  beneath  these  fibres,  and  are  covered  by 
the  green  part  of  the  leaf — and  after  it  has  absorbed  or  given 
off  the  gases  which  the  pores  transmit,  the  sap  is  returned 
towards  the  outer  part  of  the  stem,  and  through  the  vessels  of 
the  inner  bark  descends  again  to  the  root. 

4°.  Course  and  motion  of  the  sap. — In  the  living  plant,  at  least 
till  it  has  passed  maturity,  most  of  the  vessels  are  full  of  sap, 
and  this  sap  is  in  continual  motion  upwards  within  the  stem,  and 
downwards  along  its  surface  within  the  inner  bark.  In  spring 
and  autumn  the  motion  is  more  rapid.  In  winter  it  is  some- 
times scarcely  perceptible  ;  yet  the  sap,  except  when  frozen,  is 
Hipposed  to  be  rarely  quite  stationary  in  any  part  of  the  tree. 

SECTION    III.' — OF   THE    SUBSTANCES    OF   WHICH    PLANTS    CHIEFLY 
CONSIST,    AND    OF   THE    STRUCTURE    OF   THEIR    SEEDS. 

In  the  way  above  described,  the  perfect  plant  derives  from  the 


^40  SUBSTANCE   OF   PLANTS. 

soil  and  from  the  air  the  food  by  which  it  is  sustained  and  ena* 
bled  to  grow.  In  the  substance  or  stem  of  plants  thus  formed, 
and  in  their  seeds,  various  chemical  compounds  exist,  but  they 
may  all  be  included  in  three  main  groups  or  classes. 

When  the  grain  of  wheat,  barley,  oats,  rye,  Indian  corn,  &c., 
is  sent  to  the  mill  to  be  ground,  two  products  are  obtained-^the 
bran  or  husk,  and  the  flour.  When  washed  free  from  flour,  the 
bran  or  husk  is  tasteless,  insoluble  in  water,  and  woody.  It  is 
the  same  thing,  indeed,  for  the  most  part,  as  the  cellular  and 
fibrous  part  of  wood  or  straw. 

Again,  when  a  portion  of  the  flour  is  made  into  dough,  and 

Fig.  12. 


this  dough  is  kneaded  with  the  hand  under  a  stream  of  water 
upon  a  piece  of  muslin,  or  on  a  fine  sieve,  as  long  as  the  water 
passes  through  milky — there  will  remain  on  the  sieve  a  glutinous 
sticky  substance  resembling  bird-lime,  while  the  milky  water  will 
gradually  deposit  a  pure  white  powder.  This  white  powder  is 
starch,  the  adhesive  substance  which  remains  on  the  sieve  is  glvr 
te%.  Both  of  these  substances  exist,  therefore,  in  the  flour  ;  they 
both  also  exist  in  the  grain. 

Further,  when  bruised  wheat,  oats,  Indian  corn,  linseed,  or 
even  chopped  hay  and  straw,  are  boiled  in  alcohol  or  ether,  a 
portion  of  oil  or.  fat,  of  wax  and  of  resin,  is  extracted,  and  is  ob- 


THE   STARCH   GROUP. 


41 


iained  separately  by  allowing  the  solution  to  evaporate  to  dry- 
ness in  the  air. 

Thus,  from  the  seed  or  grain  we  have  obtained  four  different 
substances — the  woody  part  which  covers  it,  starch,  gluten,  and 
fat.  The  annexed  woodcut  shows  the  position  and  relative 
quantities  of  the  last  three  substances  in  the  seeds  of  wheat,  bar- 


Indian  com. 


Fig.  13. 
Wheat. 


Barley. 


ley,  and  Indian  corn.  Thus,  a  shows  the  position  of  the  oil  in 
the  outer  part  of  the  seed.  It  exists  in  minute  drops,  enclosed 
in  six-sided  cells,  which  consist  chiefly  of  gluten,  h  the  posi- 
tion and  comparative  quantity  of  the  starch,  which  in  the  heart 
of  the  seed  is  mixed  with  only  a  small  proportion  of  gluten,  c 
the  germ  or  chit  which  contains  much  gluten. 

These  substances  represent  the  three  great  classes  of  organic 
bodies  of  which  the  bulk  of  all  plants  is  made  up. 

The  woody  matter  and  the  starch  represent  what  is  called  the 
starch  group.  The  gluten  represents  the  gluten  or  ilbumen 
group.     The  oil  or  resin  represents  the  fatty  group. 

I  shall  briefly  describe  these  several  groups  or  classes  of  sub- 
stances. 

SKCTION  IV. OF   THE    STARCH   GROUP ^WOODY  FIBRE,  STARCH,    GUM, 

MUCILAGE,    SUGAR,    AND    PECTOSE,    OR   PECTIC    ACID. 

The  starch  group  comprehends  a  great  number  of  different 
substances,  possessing  different  properties,  but  all  characterised 
by  this  similarity  in  composition,  that  they  consist  of  carbon  and 
toater  only. 


i%  CELLULOSE,    STARCHES,   GUMS   AND  MUCILAGES. 

The  following  are  the  principal  substances  belonging  to  this 
class  : — 

1°.  Cellulose  or  woody  fibre. — ^This  forms  the  walls  of  the  cells 
of  plants,  the  fibres  of  cotton  and  linen,  the  woody  part  of  the 
husk  or  covering  of  the  seed,  and  a  large  portion  of  the  sub- 
stance of  wood,  hay,  straw,  &c.  It  is  insoluble  in  water,  both 
in  the  fresh  and  dry  states,  but,  as  it  exists  in  fodder,  appears, 
after  due  mastication,  to  be  in  some  degree  soluble  in  the  stom- 
achs of  animals.  It  consists  of  36  parts  by  weight  of  carbon, 
and  45  of  water. 

2°.  The  starches. — There  are  several  varieties  of  starch  besides 
that  which  occurs  in  the  flour  of  wheat,  oats,  barley,  the  pota- 
to, &c.  These  are  all  insoluble  in  cold  water,  but  give  a  jelly 
with  boiling  water.  The  Iceland  moss,  and  some  other  lichens, 
contain  a  starch  which  gives  a  jelly  with  boiling  water,  but 
which  is  somewhat  different  from  that  of  common  starch  ;  while 
the  roots  of  the  dahlia  and  the  dandelion  give  a  starch  which 
dissolves  in  boiling  water,  but  does  not  form  a  jelly,  and  falls 
again  in  a  powdery  state  as  the  solution  cools. 

Common  starch,  and  that  of  the  dandelion  and  the  lichen, 
consist,  like  woody  fibre,  of  36  parts  of  carbon  by  weight,  and 
45  of  water;  that  of  the  dahlia  contains  a  very  little  more 
water. 

3°.  The  gums.—When  common  starch  is  heated  in  an  oven 
to  300°  F.,  or  when  it  is  mixed  with  water  containing  a  little 
sulphuric  acid  and  gently  heated,  it  is  changed  into  a  soluble 
gummy  adhesive  substance,  to  which  the  name  of  dextrin  is 
given.  In  this  soluble  state,  starch  is  supposed  to  exist  abun- 
dantly in  the  sap  of  plants.  The  name  arabine  is  given  to 
gum  arable,  which  is  soluble  in  cold  water,  and  ceracine  to 
cherry  tree  gum,  which  is  insoluble  in  cold,  but  dissolves  readily 
in  boiling  water.  All  these  three  varieties  of  gum  consist,  like 
,ommon  starch  and  woody  fibre,  of  36  parts  by  weight  of  car- 
bon, united  to  45  parts  of  watei;, 

4°.   The  mucilages. — ^The  name  of  mucilage  is  given  to  gum 


CANE  AND  GRAPE  SUGARS.  43 

tragacauth,  wHch  does  not  dissolve,  but  swells  out  into  a  jelly 
when  placed  in  water — to  the  adhesive  matter  which  water  ex- 
tracts from  linseed  and  other  oily  seeds,  and  to  tlie  jelly  which 
is  obtained  from  the  roots  of  the  orchis,  (Salop,)  the  mallow, 
&c.  It  consists  of  48  parts  by  weight  of  carbon,  and  51  of 
water. 

5°.  The  sugars. — In  the  sap  of  plants  several  kinds  of  sugar 
occur;  but  those  called  cane  and  grape  sugars  are  the  most 
abundant. 

Cane  sugar  exists  in  the  sugar  cane,  the  maple,  the  beet,  the 
stalks  of  corn,  and  in  many  other  plants.  In  the  ordinary  states 
of  loaf  sugar,  crystallised  sugar,  sugar-candy,  &c.,  it  consists  of 
48  parts  of  carbon  by  weight,  and  66  of  water. 

Grape  sugar  exists  naturally  in  the  grape,  in  fruits  in  general, 
and  in  honey.  It  is  formed  artificially  when  cellulose  o.v  sta:  d-i 
is  boiled  for  a  length  of  time  in  water  made  slightly  sr^iA;  vv 
means  of  sulphuric  acid,  (oil  of  vitriol.)  It  is  less  i::veet  t.ia  i 
cane  sugar,  and  in  its  crystallised  state  consists  of  48  ol  n;iv:>3u 
by  weight,  and  84  of  water. 

The  following  table  exhibits  the  relative  composition  cf  these 
several  substances  in  a  hundred  parts,  as  nearly  as  ii  can  be 
expressed  in  whole  numbers  : — 

Cellulose  or  woody  fibre, 

Starch, 

Gum,    . 

Mucilage, 

Sugar  of  the  cane. 

Sugar  of  the  grape, 

In  stating  that  these  substances  consist  of  carbon  and  water 
only,  I  have  adopted,  for  the  sake  of  clearness  and  simplicity,  a 
mode  of  expression  which  has  not  yet  been  shown  to  be  quite 
correct.  It  is  not  certain  that  these  substances  contain  water 
in  the  proportions  above  stated,  but  they  contain  hydrogen  and 
oxygen  in  the  proportions  (1  to  8)  in  which  they  form  water. 
For  simplicity,  therefore,  we. may  suppose  these  two  elementary 


Carbon- 

Water. 

44 

56 

44 

56 

44 

56 

46 

54 

42 

58 

36 

64 

4i  PATTY  SUBSTANCES   OF  PLANTS. 

bodies  actually  to  exist  in  the  vegetable  substances  above  de» 
scribed  in  the  form  of  water. 

6°.  Pectost  and  pedic  acid. — ^The  reader  will  not  fail  to  be 
struck  with  the  remarkable  circumstance,  that  substances  so 
different  as  woody  fibre,  starch,  and  gum,  should  yet  consist  of 
the  same  elements — charcoal  and  water  united  together  in  the 
same  proportions.  In  some  vegetable  substances,  however, 
which  otherwise  resemble  starch  and  gum,  and  may  be  classed 
along  with  them,  the  hydrogen  and  oxygen  do  not  exist  exactly 
in  this  proportion.  In  fleshy  fruits,  such  as  the  plum,  peach, 
apricot,  apple,  pear,  &c.,  and  in  the  bulbs  or  roots  of  the  turnip, 
the  carrot,  the  parsnip,  &c.,  there  exists  no  starch,  but  in  its 
stead  a  substance  to  which  the  name  of  pectose  and  sometimes 
of  pectic  acid  is  given.  This  substance  is  nearly  as  nutricious  as 
starch,  and  serves  the  same  purposes  when  eaten.  It  contains, 
however,  less  hydrogen  and  more  oxygen  than  starch  does,  and 
changes  also  more  readily  into  other  substances  both  in  th« 
plant  and  in  the  stomach. 

SECTION  V. OF  THE   FATTY   SUBSTANCES   OP   PLANTS. 

The  fatty  substances  which  occur  in  plants  are  of  three  kinds 
— the  true  fats  and  oils,  the  waxes,  and  the  turpentines  and 
resins.  They  all  agree  in  containing  less  oxygen  than  would  be 
required  to  convert  their  hydrogen  into  water — ^less  than  8  to  1 
by  weight. 

1°.  The  true  fats  which  have  as  yet  been  found  in  plants  are 
divided  into  two  classes — the  solid  and  the  liquid  fats. 

a.  Solid  fats. — ^When  almond,  olive,  or  linseed  oil  is  exposed 
to  a  very  low  temperature,  a  portion  of  it  freezes  or  becomes 
solid.  This  portion  may  be  separated,  and  by  pressure  may  be, 
in  great  measure,  freed  from  the  liquid  portion. 

The  solid  part  thus  obtained  from  most  vegetable  oils  is  called 
margarine,  and  is  identical  with  the  solid  part  of  butter,  and  of 
the  fat  of  man,  of  the  horse,  and  ©f  some  other  animals.  Some 


SUBSTANCES   CONTAINING   NITROGEN.  45 

plants  jield  a  solid  fat  called  stearine,  which  is  the  same  thing 
as  the  solid  fat  of  the  cow,  the  sheep,  the  pig,  the  goat,  and 
many  ether  animals. 

h.  T<i  the  liquid  fats  the  name  of  elaine  is  given.  That 
obtained  from  the  oils  of  almonds,  olives,  &c.,  which  are  called 
fat  oils,  is  somewhat  different  from  that  of  which  linseed,  wal- 
nut, and  other  drying  oils  chiefly  consist.  The  liquid  oil  ex- 
pressea  from  the  fat  of  animals  consists  chiefly  of  the  former 
vanet.''  of  elaine. 

%°.  The  waxes. — Many  plants  produce  wax.  It  coats  the 
flowers  and  leaves  of  many  trees  and  shrubs,  and  forms  the 
beautiful  bloom  which  .covers  the  grape  and  other  fruits.  From 
these  the  bees  collect  it;  and  though  the  different  varie- 
ties of  wax  differ  somewhat  in  properties,  they  all  agree  with 
bees-wax  in  beiug  insoluble  in  water,  partially  soluble  in  alcohol, 
Qearly  without  taste  and  very  combustible. 

3^.  The  turpentines  and  resins  abound  in  trees  of  the  pine 
tribe.  They  are  all  insoluble  in  water,  but  readily  soluble  in 
alcohol;  are  more  combustible  than  either  true  fat  or  wax,  and 
contain  less  oxygen  than  either. 

Nothing  resembling  either  wax  or  resin  is  found  in  the  bodies 
of  animals. 

SECTION  VI.— OF   VEGETABLE    SUBSTANCES   CONTAINING   NirROGEN 

THE    GLUTEN    OR   ALBUMEN   GROUP. 

In  washing  the  dough  of  wheaten  flour,  we  have  seen  (p. 
iO)  that  a  portion  remains  on  the  sieve  or  muslin,  to  which  the 
name  of  gluten  is  given.  This  substance  contains  nitrogen  in 
addition  to  the  carbon,  hydrogen,  and  oxygen  which  are  present 
in  the  bodies  described  in  the  preceding  sections,  and  is  the  re- 
presentative of  an  entire  class  of  important  substances  into 
which  nitrogen  enters  as  a  constituent.  I  shall  briefly  mentiou 
the  most  important  of  these  substances. 

1^.  Gluten. — ^This  is  obtained  from  the  dough  of  wheaten 


46  ALBUMEN    tND    CASEIN. 

flour,  in  the  way  already  described.  It  is  inso''*jM3  in  ^ater, 
partly  soluble  iu  alcohol,  which  extracts  from  it  a  fatty  oil,  and 
entirely  and  easily  soluble  in  vinegar,  (acetic  acid,)  or  in  solu- 
tions of  caustic  potash  or  soda.  Besides  the  fatty  oil  which  it 
contains,  the  crude  gluten,  as  it  is  washed  from  wheaten 
flour,  consists  of  at  least  two  substances, — one  soluble  in  alco- 
hol, (glutin,)  the  other  insoluble  in  this  liquid,  v! gluten,)  and 
which  appears  closely  to  resemble  coagulated  albumen.  When 
moist,  gluten  is  nearly  colorless,  and  is  tenacious  and  adhesiye 
like  bird-lime  ;  but  when  perfectly  dry,  it  is  hard,  brittle,  and 
of  a  grey  or  brownish  color. 

2°.  Albumen. — The  white  part  of  eggs  is  called  albumen  by 
chemists.  In  the  natural  state  it  is  a  glairy  thick  liquid,  which 
can  be  diffused  through  or  dissolved  in  water,  but  which  coagu- 
lates, or  becomes  solid  and  opaque,  when  heated  to  about  180° 
of  Fahrenheit,  or  nearly  to  the  temperature  of  boiling  water. 
In  this  coagulated  state  it  is  insoluble  in  water,  or  in  alcohol 
but  dissolves  in  vinegar,  or  in  solutions  of  caustic  potash  or  soda. 
When  dried  it  becomes  hard,  brittle,  semi-transparent,  and  o 
a  brownish  color. 

When  the  expressed  juice  or  sap  of  plants  is  heated,  a  solid 
substance  coagulates,  and  separates  from  it  in  opaque  white 
flocks.  This  substance  possesses  nearly  all  the  properties  of  the 
albumen  of  the  egg,  and  is  therefore  called  vegetable  albumen. 

Albumen  exists  in  plants  not  only  in  the  liquid  state,  as  in 
the  sap  of  plants,  but  also  in  the  coagulated  state.  In  the 
husks  and  envelopes  of  many  seeds — the  bran  of  corn  for  exam- 
ple— and  in  the  solid  parts  of  woody  and  herbaceous  plants,  it 
is  found  in  this  state  in  greater  or  less  proportion. 

3°.  Casein. — ^When  rennet,  vinegar,  or  diluted  muriatic 
acid  is  added  to  milk,  it  coagulates  or  curdles,  and  a  white  curd 
separates  from  the  whey.  Alcohol  or  ether  extracts  the  fat  or 
butter  from  the  coagulated  mass,  and  leaves  pure  curd  behind. 
To  this  curd  chemists  give  the  name  of  casein. 

When  cold  water  is  shaken  up  with  oatmeal  for  half  an  hour, 


GERMINATION    OF    SEEDS.  47 

and  is  then  allowed  to  subside,  the  clear  liquid  becomes  troubled 
on  the  addition  of  a  little  acid,  and  a  white  powder  falls,  pos- 
sessing nearly  all  the  properties  of  the  casein  of  milk. 

The  sap  of  nearly  all  plants — the  expressed  juice  of  the  po- 
tato, the  turnip,  and  other  roots,  after  being  heated  to  coagu- 
late the  albumen — and  the  solution  obtained  when  the  meal  of 
the  bean,  the  pea,  and  other  legumes,  is  treated  with  warm 
water — yield,  on  the  addition  of  an  acid,  precipitates  of  this 
substance  differing  but  little  from  one  another. 

Vegetable  casein,  therefore,  is  a  constant  constituent  of  our 
best  known  and  cultivated  plants.  To  the  variety  obtained 
from  the  oat  the  name  of  avenin  has  been  given,  and  to  that 
yielded  by  the  bean,  the  pea,  and  the  vetch,  the  name  of  legumin. 

All  these  substances  are  combinations  of  a  body  called  protein, 
and  are  therefore  frequently  spoken  of  under  the  general  desig- 
nation of  protein  compounds*  They  occur  mixed  in  variable 
proportions  in  the  different  kinds  of  grain  and  roots  which  are 
used  for  food.  In  addition  to  carbon,  oxygen,  and  hydrogen, 
they  all  contain,  when  quite  dry,  about  1 6  per  cent  of  nitrogen, 
with  1  or  2  per  cent  of  sulphur,  and  most  of  them  also  a  small 
per-centage  of  phosphorus. 

SECTION    VII. OF    THE    GERMINATION    OF    SEEDS    AND   THE    GROWTH 

OF    PLANTS. 

When  a  seed  is  committed  to  the  earth,  if  the  warmth  and 
moisture  are  favorable,  it  begins  to  sprout.  It  pushes  a 
shoot  upwards,  it  thrusts  a  root  downwards,  but,  until  the  leaf 
expands  and  the  root  has  fairly  entered  the  soil,  the  young  plant 
derives  no  nourishment  other  than  water,  either  from  the  earth 
or  from  the  air.  It  lives  on  the  starch  and  gluten  contained  in 
the  seed.  But  these  substances,  though  capable  of  being  sepa- 
rated from  each  other  by  means  of  water,  as  described  in  a 

♦  For  an  account  of  protein  and  its  compounds,  see  my  Lectures  on  Agrif 
onUurai  Chemistry,  2d  edition,  p.  5. 


4S  CHANGE    OF    STARCH   INTO    SUGAR. 

previous  section,  (p.  40,)  are  neither  of  them  soluble  in  water. 
Hence  they  cannot,  without  undergoing  a  previous  chemical 
change,  be  taken  up  into  the  sap  and  conveyed  along  the  ves- 
sels of  the  young  shoot  they  are  destined  to  feed.  But  it  is  so 
arranged  in  nature  that,  when  the  seed  ^rst  sprouts,  there  is 
produced  at  the  base  of  the  germ,  from  a  portion  of  the  gluten, 
a  small  quantity  of  a  white  soluble  suHtance  called  diastase. 
This  substance  exercises  so  powerful  an  eflfect  upon  the  starch 
as  almost  immediately  to  render  it  soluble  in  the  sap,  which  is 
thus  enabled  to  take  it  up  and  convey  it  by  degrees,  just  as  it  is 
wanted,  <  the  shoot  or  to  the  root.*  The  starch,  when  thus 
changed  and  rendered  soluble,  becomes  the  substance  called 
dextrin,  which  we  have  already  described,  (p.  42.) 

In  the  oily  seeds  which  contain  no  starch,  the  mucilage  and 
the  oil  take  the  place  of  starch  in  nourishing  the  young  sprout. 

As  the  sap  ascends  it  becomes  sweet — the  dextrin  formed 
from  the  starch  is  further  changed  into  sugar.  When  the  shoot 
first  becomes  tipped  with  green,  this  sugar  again  is  changed 
into  cellulose  or  woody  fibre,  of  which  the  stem  of  perfect 
plants  chiefly  consists.  By  the  tune  that  the  food  contained  in 
the  seed  is  exhausted — often  long  before — the  plant  is  able  to 
live  by  its  own  exertions,  at  the  expense  of  the  air  and  the  soil. 

This  change  of  the  sugar  of  the  sap  into  cellular  or  woody 
fibre  is  observable  more  or  less  in  all  plants.  When  they  are 
shooting  fastest  the  sugar  is  most  abundant — not,  however,  in 
those  parts  which  are  actually  shooting  up,  but  in  those  which 
convey  the  sap  to  thS'  growing  parts.    Thus  the  sugar  of  the 

*  In  malting  barley,  it  is  made  to  sprout  a  certain  length,  and  the  growth 
is  then  arrested  by  heating  and  drying  it.  Mashed  barley,  before  sprout- 
ing, will  not  dissolve  in  water ;  but  when  sprouted,  the  whole  of  the  starch 
(the  flour)  it  contains  dissolves  readily  by  a  gentle  heat,  and  is  changed  into 
soluble  dextrin.  The  diastase  formed  during  the  germination  effects  this 
By  further  heating  in  the  brewer's  wort,  this  dextrin  is  converted  into  sugar 
by  the  agency  of  the  same  diastase,  as  it  is  also  in  the  growing  plant.  We 
can  thus  imitate  by  art;  and,  in  brewing,  we  do  imitate  what  takes  plaoe 
naturally  in  the  living  vegetable. 


FORMATION    OF   CELLULAR    FIBRE.  49 

ascending  sap  of  the  maple  and  the  alder  disappears  in  the  leaf 
and  in  the  extremities  of  the  twig.  Thus  the  sugar-cane  sweet- 
ens only  a  certain  distance  above  the  ground,  up  to  where  the 
new  growth  is  proceeding  ;  and  thus  also  the  young  beet  and 
turnip  abound  most  in  sugar — while  in  all  these  plants  the 
sweet  principle  diminishes  as  the  year's  growth  draws  nearer  to 
a  close. 

In  the  ripening  of  the  ear,  also,  the  sweet  taste  at  first  so 
perceptible  in  young  grain  gradually  diminishes,  and  finally  dis- 
appears. The  sugar  of  the  sap  is  here  changed  into  the  starch 
of  the  grain,  which,  as  above  described,  is  afterwards  destined, 
when  the  grain  begins  to  sprout,  to  be  reconverted  into  sugar 
for  the  nourishment  of  the  rising  germ. 

In  the  ripening  of  fruits  a  different  series  of  changes  presents 
itself.  The  fruit  is  at  first  tasteless,  then  becomes  sour,  and  at 
last  sweet.  In  this  case,  either  the  acid  of  the  unripe  is  changed 
into  the  sugar  of  the  ripened  fruit,  or  a  portion  of  the  other 
constituents  of  the  fruit — its  cellulose  and  pectose — are  con- 
verted into  sugar,  and  disguise  the  acid. 

SECTION   VIII. HOW   THE    CELLULAR   OR   WOODY   MATTER    OF 

PLANTS    IS    FORMED    FROM   THEIR   ORGANIC    FOOD. 

The  substance  of  plants — their  solid  parts,  that  is — consists 
chiefly,  as  we  have  already  stated,  of  cellular  fibre,  the  name 
given  to  the  fibrous  substance  of  which  wood  evidently  consists. 
It  is  interesting  to  inquire  how  this  substance  can  be  formed 
from  the  compounds — water  and  carbonic,  humic,  ulmic,  and 
other  acids — of  which  the  organic  food  of  plants  in  a  great 
measure  consists.     Nor  is  it  difficult  to  find  an  answer. 

1°.  It  will  be  recollected  that  the  leaf  drinks  in  carbonic 
acid  from  the  air,  and  delivers  back  its  oxygen,  retaining  only 
its  carbon,  (p.  38.)  It  is  also  known  that  water  abounds  in 
the  sap.  Hence  carbon  and  water  are  abundantly  present  in 
the  pores  or  vessels  of  the  green  and  living  leaf.  Now,  as  cel- 
3 


50  FORMATION    OF   CELLULAR   FIBRE. 

lulose  or  woody  fibre  consists  only  of  carbon  and  water  chemically 
combined  together,  it  is  easy  to  see  how,  when  the  carbon  and 
water  meet  in  the  leaf,  cellular  fibre  may  be  produced  by  their 
mutual  combination. 

2°.  If,  again,  we  inquire  how  this  important  constituent  of 
plants  may  be  formed  from  the  other  substances,  which  enter 
by  their  roots — from  the  humic  acid  (p.  21)  for  example — the 
answer  is  equally  ready.  This  acid  also  consists  of  carbon  and 
water  only — 50  lb.  of  carbon  with  37^  of  water  forming  87  J  of 
humic  acid — so  that,  when  it  is  conveyed  by  the  roots  into  the 
sap  of  the  plant,  all  the  materials  are  present  from  which  the 
cellular  fibre  may  be  produced. 

3°.  Nor  is  it  more  diflBcult  to  understand  how  the  starch  of 
the  seed  may  be  conyerted  into  sugar,  and  this  again  into  cel- 
lular fibre  ;  or  how,  conversely,  sugar  may  be  changed  into 
starch  in  the  ear  of  corn,  or  cellular  fibre  into  sugar  during  the 
ripening  of  the  winter  pear  after  its  removal  from  the  tree. 
Any  one  of  these  substances  may  be  represented  by  carbon  and 
water  only.  In  the  interior  of  the  plant,  therefore,  it  is  obviouj 
that  if  any  one  of  them  is  present  in  the  sap,  the  elements  are 
at  hand  out  of  which  any  of  the  others  may  be  produced.  In 
what  way  they  really  are  produced,  the  one  from  the  other, 
and  by  what  circumstances  these  transformations  are  favored, 
it  would  lead  into  too  great  detail  to  attempt  here  to  explain.* 

We  cannot  help  admiring  the  varied  purposes  to  which  in 
nature  the  same  elements  are  applied, — and  from  how  small  a 
number  of  materials,  substances  the  most  varied  in  their  pro* 
perties  are  in  the  living  vegetable  daily  produced. 

*  For  fuller  and  more  precise  explanations  ou  these  interesting  topic% 
see  the  Author's  Lectures  on  Agrictdtural  Chemistry  and  Geology,  2d  edition, 
PMtl. 


NECESSITY   OF  NITROGEN  TO  THE   GROWTH   OF  PLANTS.         51 


SECTION  IX. — OF  THE  NECESSITY  OF  NITROGEN,  OR  OF  SUBSTANCES 
CONTAINING  IT,  TO  THE  GROWTH  OP  THE  PLANT,  AND  OF  THB 
FORMS    IN   WHICH    IT   MAY    ENTER   THE   ROOTS. 

But  a  substance  containing  nitrogen  is  necessary  to  the  pro- 
duction of  those  beautiful  and  varied  changes  which  take  place 
in  the  sap  of  the  plant  at  the  different  stages  of  its  growth. 

"We  have  seen  that,  during  germination,  the  insoluble  gluten 
of  the  seed  is  partly  changed  into  a  soluble  substance — diastase 
— by  which  the  first  alteration  of  the  insoluble  starch  into  solu- 
ble dextrin  is  effected.  The  remainder  of  the  gluten  ascends 
or  descends  by  degrees  with  the  sap,  in  some  soluble  form  which 
is  not  yet  clearly  understood,  and,  if  not  actually  the  cause  of 
the  successive  changes  which  the  starch,  sugar,  and  gum  of 
the  sap  undergo,  it  is  at  least  always  present  when  they  are 
produced. 

At  every  point  in  the  growing  shoot  and  root  some  compound 
of  nitrogen  must  be  present,  if  it  is  to  increase  in  size, — since 
in  the  interior  of  every  new  cell  the  presence  of  such  a  com- 
pound in  minute  quantity  can  be  distinctly  recognised.  In  the 
young  radicles  of  the  sprouting  barley  there  are  32  per  cent,  of 
a  substance  containing  nitrogen,  while  the  grain  itself  contains 
only  14,  This  substance  seems  to  preside  over  the  change  of 
the  soluble  substances  contained  in  the  sap,  into  the  insoluble 
fibre  of  the  cell.  The  change  of  the  sugar  and  gum  of  the 
sap  into  the  starch  of  the  ear  always  takes  place  also  in  the 
presence  of  a  substance  containing  nitrogen.  In  the  young 
seed  it  is  present  in  much  larger  proportion  than  when  the  seed 
is  matured.  In  the  pea,  when  beginning  to  form  in  the  shell,  it 
constitutes  48  per  cent,  of  the  whole  weight,  (Payen,)  while  in 
the  ripe  pea  it  does  not  exceed  one-half  the  quantity. 

When  the  starch  or  sugar  undergoes  a  change,  the  nitrogen- 
ous compound  undergoes  a  simultaneous  change  ;  and  as  the 
transformation  of  the  starch  of  the  seed  into  tie  sugar  of  th« 


62  FORMS  IN  WHICH   NITBOGEN   ENTERS  INTO   PLANTS. 

sap  is  attended  by  the  change  of  its  gluten  into  diastase  and 
other  soluble  compounds,  so  the  converse  change  of  the  sugar 
of  the  sap  into  the  starch  of  the  ear  is  attended  by  a  converse 
production  of  the  insoluble  gluten  of  the  ripening  grain. 

It  has  also  been  ascertained  that  the  leaves  of  growing  plants 
are  in  the  sunshine  always  giving  off  nitrogen,  in  quantity  which 
varies  with  the  kind,  and  probably  the  age,  of  the  plant,  and 
with  the  time  during  which  it  has  been  exposed  to  the  sun's 
rays.  This  nitrogen  appears  to  be  derived  from  gluten  and 
other  nitrogenous  (protein)  compounds,  which  are  continually 
undergoing  changes  in  the  sap,  and  which  are  necessary  to  the 
ordinary  processes  of  vegetable  growth. 

The  necessity  of  nitrogen  to  the  growth  of  the  plant  in  all 
its  stages  is  thus  fully  established  ;  and  hence  the  utility,  estab- 
lished by  long  practical  experience,  of  applying  manures  iu 
which  nitrogen  is  contained. 

It  has  not  yet  been  proved  in  what  form  of  combinatiou 
nitrogen  is  most  fitted  to  promote  the  growth  of  our  cultivated 
crops.  It  usually  finds  its  way  into  the  roots  of  plants  iu  the 
form  of  nitric  acid,  of  ammonia,  of  other  organic  alkalies  con- 
taining nitrogen,  (p.  30.)  or  of  the  compounds  of  these  alkalies 
with  the  humic  and  ulmic  acids,  which  are  so  extensively  pro- 
duced in  the  soil  itself.  Animal  manures  may  owe  part  of  their 
peculiar  beneficial  action  to  their  supplying  other  compounds  of 
nitrogen — ^protein  compounds,  perhaps,  in  a  soluble  form — which 
the  plant,  with  still  less  trouble  to  itself,  can  convert  into  por- 
tions of  its  own  substance. 

The  plant  grows  rapidly  by  the  aid  of  the  ready-formed 
gluten  of  the  seed, — why  should  it  not  thrive  well  also  by  the 
aid  of  similar  compounds  placed  within  its  reach  in  the  soil  and 
absorbed  by  its  roots  ?  There  seems,  indeed,  very  little  solid 
foundation  for  the  opinion  held  by  some,  that  the  plants  in  our 
cultivated  fields  derive  the  whole  of  their  nitrogen  from  ammouij* 
and  nitric  acid  together — still  less  that  they  obtain  it  from 
ammonia  alone. 


FORMS   IN  'WHICH   NITROGEN  MAY  ENTER  ROOTS.  63 

The  plant  that  grows  on  the  surface  of  common  vinegar,  and 
inakes  it  thick  and  glairy,  is  formed  from  the  vinegar*  itself, 
and  from  a  nitrogenous  substance  resembling  gluten,  which  the 
liquid  vinegar  holds  in  solution.  So  the  mould  which  grows  on 
flour  paste  is  formed  from  the  starch  and  the  gluten  of  the  flour, 
end  the  minute  plant  which  forms  the  yeast  in  the  brewer's  vat 
is  produced  from  the  sugar  of  the  wort  and  the  changed  gluten 
of  the  barley. 

In  all  these  cases  the  substance  of  the  plant  is  formed  by  the 
direct  appropriation  of  compounds,  which  bear  a  close  analogy 
to  those  of  which  its  own  parts  consist  ;  and  though  the  mould 
plants  above  mentioned  are  very  different  in  kind  from  those  we 
raise  for  food,  yet  the  mode  in  which  they  are  built  up  is  very 
similar  to  that  by  which  the  solid  parts  of  larger  plants  are 
really  produced  from  the  substances  contained  in  the  sap.  If, 
then,  those  substances  from  which  their  growing  parts  are  thus 
known  to  be  built  up  can  be  conveyed  directly  into  the  circula- 
tion of  our  cultivated  plants  by  their  roots,  it  is  reasonable  to 
suppose  that  their  growth  may  be  promoted  by  them  at  least  as 
well  as  if  the  roots  took  up  only  carbonic  acid  to  supply  the  car- 
bon, and  ammonia  to  supply  the  nitrogen. 

In  other  words,  the  probabilities  are,  I  think,  in  favor  of  the 
view  that  animal  or  vegetable  substances  containing  nitrogen, 
when  brought  into  a  soluble  state  by  fermentation,  may  enter 
directly  into  the  roots,  and  feed  our  crops,  without  being  first 
decomposed  either  into  ammonia  or  into  nitric  acid.  The  subject 
is  deserving,  therefore,  of  being  made  matter  of  direct  experi- 
ment in  the  field  or  garden. 

*  Pure  vinegar,  like  starch  and  cellular  fibre,  consists  of  carbon  and 
water  alone,  50  of  carbon  and  56  of  water  forming  106  of  vinegar. 


CHAPTER  IV. 

Of  the  inorganic  constituents  of  plants. — Potash,  soda,  lime,  magnesia,  Bilica, 
alumina,  oxide  of  iron,  oxide  of  manganese,  sulphur,  sulphuric  acid,  phos- 
phorus, phosphoric  acid,  chlorine,  iodine,  fluorine. — Immediate  source  of 
these  constituents  of  plants. — The  quantity  contained  in  plants,  and  in 
parts  of  plants,  varies  with  many  circumstances. — The  composition  or 
quality  of  the  inorganic  constituents  in  plants. — It  varies  also  with  many 
circumstances. — Average  quantity  of  each  constituent  in  certain  common 
crops,  and  in  a  series  of  crops. — Practical  deductions  from  a  knowledge 
of  the  inorganic  constituents  of  plants. 

SECTION   I. — SOURCE    OF   THE   EARTHY   MATTER   OP   P3LANTS,    AND 
SUBSTANCES    OF   WHICH   IT   CONSISTS. 

When  plants  are  burned,  they  always  leave  more  or  less  of 
ash  behind.  This  ash  varies  in  quantity  in  different  plants,  in 
different  parts  of  the  same  plant,  in  different  specimens  even  of 
the  same  kind,  and  of  the  same  part  of  a  plant,  especially  if 
grown  upon  different  soils  ;  yet  it  is  never  wholly  absent.*  It 
is  as  necessary  to  their  existence  in  a  state  of  perfect  health,  as 
any  of  the  elements  which  constitute  the  organic  or  combustible 
part  of  their  substance.  They  must  obtain  it,  therefore,  along 
with  the  food  on  which  they  live.  It  is,  in  fact,  a  part  of  their 
natural  food,  since  vrithout  it  they  become  unhealthy.  We  shall 
speak  of  it,  therefore,  as  the  inorgatiic  food  of  plants. 

We  have  seen  that  all  the  elements  which  are  necessary  to 
the  production  of  the  cellular  fibre,  and  of  the  other  organic 
parts  of  the  plant,  may  be  derived  either  from  the  air,  from  the 
carbonic  acid  and  watery  vapor  taken  in  by  the  leaves,  or  from 

*  The  only  known  exceptions  occur  in  the  mould  plants — as  in  the  myco- 
derma  vini,  which  grows  on  pure  vinegar,  that  which  grows  on  solutions  of 
milk  sugar,  &g.    By  these  no  trace  of  ash  is  left. 


INORGANIC    OR   EARTHY   MATTER    OF    PLANTS.  55 

the  soil  through  the  medium  of  the  roots.  In  the  air,  however, 
only  rare  particles  of  inorganic  or  earthy  matter  are  known  to 
float,  and  tliese  are  in  a  solid  form,  and  therefore  unable  to  en- 
ter the  minute  pores  of  the  leaves.  Hence  the  earthy  matter 
which  constitutes  the  ash  of  plants  must  all  be  derived  from  the 
soil. 

The  earthy  part  of  the  soil,  therefore,  serves  a  double  use.  It 
is  not,  as  some  have  supposed,  a  mere  substratum,  in  which  the 
plant  may  so  fix  and  root  itself  as  to  be  able  to  maintain  its  up- 
right position  against  the  force  of  winds  and  tempests  ;  but  it  is 
a  storehouse  of  food  also,  from  which  the  roots  of  the  plant  may 
select  such  earthy  substances  as  are  necessary  to,  or  are  fitted 
to  promote,  its  growth. 

The  ash  of  plants  consists  of  a  mixture  of  several,  sometimes 
of  as  many  as  fourteen,  different  substances.  These  substances 
are  the  following  : — 

1.  Potash. — The  common  pearl-ash  of  the  shops  is  a  com- 
pound of  potash  with  carbonic  acid,  or  it  is  a  carbonate  of  potash. 
By  dissolving  the  pearl-ash  in  water,  and  boiling  it  with  quick- 
lime, the  carbonic  acid  is  separated,  and  potash  alone,  or  caus- 
tic potash,  as  it  is  often  called,  is  obtained. 

2.  Soda. — The  common  soda  of  the  shops  is  a  carhonate.  of 
soda.  By  boiling  it  with  quick-lime,  the  carbonic  acid  is  sepa- 
rated, as  in  the  case  of  pearl-ash,  and  pure  or  caustic  soda  re- 
mains. The  proportions  to  be  used  are  1  lb.  of  the  carbonate 
to  a  J  lb.  of  lime  and  10  lb.  of  water. 

3.  Lime. — This  is  familiar  to  every  one  as  the  lime-shdls,  or 
unslaked  lime  of  the  lime-kilns.  The  unburned  lime-stone  is  a 
carbonate  of  lime,  the  carbonic  acid  in  this  case  being  separated 
from  the  lime  by  the  roasting  in  the  kiln. 

4.  Magnesia. — This  is  the  calcined  magnesia  of  the  shops. 
The  uncalcined  is  a  carbonate  of  magnesia,  from  which  heat 
drives  off  the  carbonic  acid. 

5.  Silica. — This  is  the  name  given  by  chemists  to  the  sub- 
stance of  flint,  of  quartz,  of  rock  crystal,  and  of  siliceous  sands 


66  OXIDSS   OF   IRON,    MANGANESE,    &C. 

and  sandstones.  It  is  particularly  abundant  in  the  straws  and 
grasses,  and  in  the  glaze  of  the  bamboo  and  other  canes. 

6.  Alvmina  is  the  pure  earth  of  alum,  obtained  by  dissolving 
alum  in  water,  and  adding  liquid  ammonia  (hartshorn)  to  the 
solution.  It  forms  about  two-fifths  of  the  weight  of  porcelain 
and  pipe-clays,  and  of  some  other  very  stiff  kinds  of  clay.  It 
exists  abundantly  in  most  soils,  but  as  an  essential  constituent 
of  plants  it  has  hitherto  been  met  with  only  in  the  ash  of  the 
club  mosses. 

T.  Oxide  of  iron. — The  most  familiar  form  of  this  substance  is 
the  rust  that  forms  on  metallic  iron  in  damp  places.  It  is  a 
compound  of  iron  with  oxygen,  hence  the  name  oxide. 

There  are,  however,  two  oxides  of  iron.  The  rci,  which  gives 
its  color  to  rust  and  to  our  red  soils.  This  oxide  is  insoluble  in 
water,  and  has  the  property  of  absorbing  ammonia  to  a  certain 
extent. 

The  black  oxide  gives  their  color  to  many  blue  clays.  It  is  so- 
luble in  weak  acids,  is  produced  from  the  red  oxide  by  the  ac- 
tion of  organic  matter  in  the  soil,  and  is  believed,  when  so  pro- 
duced, to  be  very  noxious  to  the  roots  of  plants. 

8.  Oxide  of  manganese  is  a  dark  brown  powder,  which  con- 
sists of  oxygen  in  combination  with  a  metal  resembling  iron,  to 
which  the  name  of  manganese  is  given.  It  usually  exists  in 
plants  and  soils  in  very  small  quantity  only. 

9.  Sulphur. — ^This  substance  is  well  known.  It  is  present  in 
nearly  all  the  parts  of  plants  and  animals.  It  exists  largely  m 
mustard  seed,  is  a  necessary  constituent  of  the  gluten  of  wheat, 
of  the  white  of  the  egg,  of  the  fibre  of  beef,  and  of  the  curd  of 
milk,  and  forms  one-twentieth  part  of  the  weight  of  hair  and 
wool.  When  sown  along  with  turnip  seed,  it  is  said  to  prevent 
the  attack  of  the  fly. 

Sulphuric  Acid,  or  oil  of  vitriol,  has  been  already  described. 
It  forms,  with  potash,  sulphate  of  potash  ;  with  soda,  sulphate  of 
soda,  or  Glauber's  salts  ;  with  ammonia,  sulphate  of  ammonia ; 
with  lime,  sulphate  of  livie,  or  gypsum  ;  with  magnesia,  sulphatt 


PHOSPHORUS   AND   CHLORINE.  67 

of  magnesia,  or  Epsom  salts  ;  with  alumina,  sulphate  of  alumina, 
which  exists  in  alum  ;  and  with  oxide  of  iron,  sulphate  of  iron, 
or  green  vitriol.  When  the  sulphate  of  potash  is  combined  with 
sulphate  of  alumina,  it  forms  common  alum. 

10.  Phosphorus  and  phosphoric  acid  have  been  already  de- 
scribed, (pp.  9  and  33.) 

Phosphoric  acid  forms  phosphates  with  potash,  soda,  ammonia, 
lime,  and  magnesia.  When  bones  are  burned,  a  large  quantity 
of  a  white  earth  remains,  (bone  earth,)  which  is  chiefly  a  phos- 
phate of  lime,  consisting  of  lime  and  phosphoric  acid,  in  the 
proportion  of  48J  of  phosphoric  acid  to  51|  of  lime.  Phosphate 
of  lime  is  present  in  the  ash  of  plants  generally.  Phosphate  of 
magnesia  is  contained  most  abundantly  in  the  ash  of  wheat, 
barley,  and  other  varieties  of  grain.  It  exists  also  in  beer,  to 
the  amount  sometimes  of  100  grains  in  a  gallon. 

11.  Chlorine. — This  is  a  very  suffocating  gas,  of  a  pale,  yellow- 

Fig.  14 


ish  green  color,  which  gives  its  peculiar  smell  to  chloride  of 
lime,  and  is  used  for  bleaching  and  disinfecting  purposes.  It  is 
readily  obtained  by  pouring  muriatic  acid  (spirit  of  salt)  upon 
the  black  oxide  of  manganese  of  the  shops,  contained  in  a  flask, 
and  applying  a  gentle  heat,  as  in  the  annexed  figure.  If  the 
flask  be  of  colorless  glass,  the  color  of  the  gas  will  imi^e^ 


18  lODIKE   AND   BROMINE. 

ately  become  perceptible,  and  its  smell  will  diffuse  itself  through 
the  room.  This  gas  is  2^  times  heavier  than  common  air,  and 
a  burning  taper  plunged  into  it  is  speedily  extinguished.  In 
combination  with  the  metallic  bases  of  potash,  soda,  lime,  and 
magnesia,  it  forms  the  chlorides  of  potassium,  sodium,)  common 
salt),  calcium,  and  magnesium  ;*  and  in  one  or  other  of  these 
states  it  generally  enters  into  the  roots  of  plants,  and  exists  in 
their  ash. 

Iodine  is  a  solid  substance  of  a  grey  color  and  metallic  lus- 
tre, very  much  resembling  filings  of  lead.  It  has  a  peculiar 
odor,  not  unlike  that  of  chlorine,  an  acrid  taste,  and  stains  the 
fingers  of  a  brown  color.  It  is  distinguished  by  two  proper- 
ties— ^by  being  changed  into  a  beautiful  violet  vapor  when 
heated,  and  by  giving  with  starch  a  beautiful  blue  compound. 
It  occurs  in  small  quantities  in  sea  water,  and  in  marine  and 
many  fresh-water  plants.  In  still  smaller  proportion,  it  has 
been  recently  detected  in  wood  ashes  and  in  those  of  land  plants, 
and  it  probably  forms  a  constant  though  very  minute  constitu- 
ent of  all  the  plants  we  raise  for  food. 

Like  their  chlorine,  they  will  obtain  it  generally  from  the 
soil  through  their  roots,  though,  as  it  has  been  detected  in  the 
atmosphere,  they  may  derive  some  of  this  element  from  the  rain 
water  that  falls  on  their  leaves. 

Bromine  is  a  dark  brownish  red  heavy  liquid,  possessed  of  a 
strong  odor,  giving  a  yellowish  red  vapor,  and  coloring 
starch  yellow.  It  also  exists  in  sea  water,  in  certain  salt 
springs,  and  has  been  detected  in  the  ashes  of  certain  plants. 
It  probably  accompanies  chlorine  and  iodine  into  all  plants, 
though  the  proportion,  which  is  still  less  than  that  of  iodine, 
has  hitherto  prevented  its  presence  from  being  detected. 

*  Potash,  soda,  lime,  and  magnesia,  are  compounds  of  the  metals  hero 
named  with  oxygen.  It  is  a  very  striking  fact,  that  the  suflFocating  gas 
chlorine,  when  combined  with  sodium,  a  metal  which  takes  fire  when 
placed  upon  hot  wf^^r,  should  form  the  agreeable  and  necessary  condiment 
common  salL 


VABIATION    IN   THE    QUANTITY   OF   ASH   IN   PLANTS,  59 

As  chlorine  forms  chlorides,  so  iodine  forms  iodides,  and  hromine 
forms  iromides  with  the  metals  already  mentioned.  The  chlo- 
rine is  the  only  one  of  these  three,  the  presence  of  which  in 
plants  is  at  present  believed  to  be  of  any  importance  in  a  prac- 
tical point  of  view. 

Fluorine  is  a  very  corrosive  gas,  of  which  little  is  yet  known. 
It  exists  in  small  quantity  in  the  teeth  and  bones,  and  in  the 
blood  and  milk,  of  animals.  Traces  of  it  also  have  been  detect- 
ed in  the  ashes  of  some  plants  ;  so  that  it  is  probably  necessary 
to  the  growth  of  both  animals  and  vegetables.  With  metals, 
it  forms  fluorides  ;  and  fluoride  of  calcium,  or  fluor  spar,  is  the 
best  known  and  most  common  of  its  combinations. 

Such  are  the  inorganic  substances  usually  found  mixed  or 
combined  together  in  the  ash  of  plants.  It  has  already  been 
observed,  that  the  quantity  of  ash  left  by  a  given  weight  of 
vegetable  matter  varies  with  a  great  many  conditions.  This 
fact  deserves  a  more  attentive  consideration. 

SECTION  II. OF  THE  DIFFERENCES  IN  THE  QUANTITY  OF  ASH 

LEFT  BY  PLANTS,  AND  BY  THEIR  SEVERAL  PARTS. 

1.  The  quantity  of  ash  yielded  by  different  plants  is  unlike. 
Thus  1000  lb.  of  the  following  vegetable  substances,  in  their 
ordinary  state  of  dryness,  leave  of  ash,  on  an  average. 


Wheat,  about  20  lb. 

"Wheat  straw,  50  lb. 

Barley,      -      30 

Barley  straw,  50 

Oats,          -      40 

Oat  straw,       60 

Rye,          -     20 

Rye  straw,      40 

Indian  com,     15 

Indian  com  do.50 

Beans,       -      30 

Pea  straw,       50 

Peas,         -     30 

Meadow  hay,  - 

-      50  to  100  lb. 

Clover  hay, 

-      90 

Eye-grass  hay, 

-      95 

Potatoes, 

8  to  15 

Turnips, 

5  to    8 

Carrots, 

.      15  to  20* 

See  Lectures  on  Agricultural  Chemistry  and  Geology. 


60     VARIATION    IN   THE    QUANTITY   OF   IN  ORGANIC   MATTER,  &C. 

So  that  the  quantity  of  inorganic  food  required  by  differeiAt 
vegetables  is  greater  or  less  according  to  their  nature  ;  and  if 
a  soil  be  of  such  a  kind  that  it  can  yield  only  a  small  quantity 
of  this  inorganic  food,  then  those  plants  only  will  grow  well 
upon  it  to  which  this  small  supply  will  prove  sufSeient.  Hence 
trees  may  grow  where  arable  crops  fail  to  thrive,  because  many 
of  the  former  require  and  contain  comparatively  little  inorganic 
matter.     Thus  the  weight  of  ash  left  by  1000  lb.  of 

Elm  wood  is  19  lb.  Birch  wood  is  3  J  lb. 

Poplar,      -     20  Pine,  -     li  to  3 

Willow,     -      4J  Oak,  -    2 

Beecb,      -      ll  to  6  Ash,  -    1  to  6 

The  elm  and  the  poplar  contain  about  as  much  inorganic 
matter  as  the  grain  of  wheat,  but  very  much  less  than  any  of 
the  Straws  or  grasses.  How  much  less  also  does  the  oak  con- 
tain than  either  the  elm  or  the  poplar  1 

2.  The  quantity  of  inorganic  matter  varies  in  different  parts 
of  the  same  -plant.  This  is  shewn  clearly  by  the  different  pro- 
portions of  ash  left  by  the  grain  and  by  the  straw  of  our  culti- 
vated crops,  as  given  in  the  preceding  table.  It  appears,  also, 
by  the  following  comparison  of  the  quantities  left  by  1000  lb.  of 
the  different  parts  of  some  of  our  cultivated  plants  in  their  dry 
state.    Thus — 


Roots  or  tuber. 

G: 

-ain  or 

seed. 

Straw  or  stalks. 

Leaves. 

Turnip, 

80  lb. 

25  1b. 

—  lb. 

130  lb. 

Potato, 

40  " 

— 



180  " 

Wheat, 

— 

20  " 

50  « 

Pea,   . 

— 

30  " 

50  " 

130  " 

Tobacco, 

70  " 

40  " 

100  " 

230  " 

In  trees,  also,  the  leaves  contain  a  much  larger  proportion  of 
inorganic  matter  than  the  wood.  Thus,  1000  lb.  of  the  dry 
wood  and  leaves  of  the  following  trees  left  of  ash  respectively — 

Seed. 


601b. 


Wood. 

Leaves. 

Willow, 

.    44  lb. 

82  lb. 

Beech,   . 

.    4     " 

42  " 

Birch,    . 

.     34" 

50  " 

Pine, 

.     3     " 

20  to  30 

Elm,      . 

.  1?     " 

120 

IT    VARIES    ALSO    WITH   THE    SOIL.  61 

It  appears,  therefore,  that  by  far  the  largest  proporlion  of 
the  inorganic  matter  which  is  withdrawn  from  the  soil  by  a  crop 
of  corn  is  returned  to  it  again,  by  the  skilful  husbandman,  in 
the  fermented  straw.  In  the  same  way  also  nature,  in  causing 
the  trees  periodically  to  shed  their  leaves,  returns  with  them  to 
the  soil  a  very  large  portion  of  the  soluble  inorganic  substances 
which  had  been  drawn  from  it  by  their  roots  during  the  season 
f/f  growth. 

Thus  an  annual  top-dressing  is  naturally  given  to  the  land 
where  forests  grow;  and  that  which  the  roots  from  spring  to 
autumn  are  continually  sucking  up,  and  carefully  collecting  from 
considerable  depths,  winter  strews  again  on  the  surface  in  the 
form  of  decaying  leaves,  so  as,  in  the  lapse  of  time,  to  form  a 
ricQ  and  fertile  soil.  Such  a  soil  niust  be  propitious  to  vegeta- 
ble growth,  since  it  contains  or  is  made  up  of  those  very  mate- 
rials of  which  the  inorganic  substance  of  former  races  of  vege- 
tables had  been  almost  entirely  composed. 

3.  It  varies  in  quantity  in  different  portions  of  the  same  part 
of  the  plant.  Thus,  if  a  tall  stalk  of  wheat,  oats,  or  barley 
straw  be  cut  into  four  equal  parts,  and  these  be  burned  sepa- 
rately, the  lowest  portion  will  generally  leave  the  smallest,  the 
highest  portion  the  greatest  per  centage  of  ash.  If  the  bottom 
of  the  stalk,  for  example,  leave  3|  or  4  per  cent.,  the  next  por- 
tion will  leave  5  or  6,  the  third  6  or  t,  and  the  highest  perhaps 
8  or  9.  This  is  a  very  interesting  and  curious  fact,  not  hitherto 
noticed  by  experimenters,  though  evidently  of  great  interest  in 
connection  with  the  inorganic  food  of  plants. 

In  some  cases  this  diflference  is  not  observed,  while  in  others 
the  largest  proportion  of  ash  is  left  by  the  bottom  part  of  the 
straw.  These  exceptions,  however,  occur  generally  in  stunted 
grain,  which  has  grown  upon  an  unfavorable  soil,  or  has  been 
injured  by  the  season. 

4.  The  quantity  of  inorganic  matter  often  differs  in  different 
specimens  and  varieties  of  the  same  plant.  Thus  1000  lb.  of  wheat 
Btraw,  grown  at  different  places,  gave  to  four  different  experi- 


t§  UIFFERS  WITH  VARIETY  AND  SOIL. 

menters  43,  44,  35,  and  155  lb,  of  ash  respectively.  Wheat 
straw,  therefore,  does  not  always  leave  the  same  quantity  of 
ash.  The  same  is  true  also  of  other  kinds  of  vegetable  pro- 
iuce. 

This  fact,  as  well  as  the  variation  of  the  quantity  of  ash  with 
.Jie  part  of  the  plant,  is  shown  by  the  following  table  of  the 
proportions  of  ash  left  by  the  several  parts  of  two  different 
varieties  of  oats  grown  on  different  soils,  (Norton) — 


Hopeton  oat 

Potato  oat 

Grain, 

2.14 

2.22 

Husk, 

6.47 

6.99 

Straw, 

4.98 

8.62 

Leaf, 

8.44 

14.59 

Cliafl^ 

16.53 

18.59 

Here  not  only  do  the  different  parts  of  the  same  plant,  but 
similar  parts  also  of  different  plants  of  the  same  species,  leave 
very  different  proportions  of  ash. 

To  what  is  this  difference  owing  ?  Is  it  to  the  nature  of  the 
soil,  or  does  it  depend  upon  the  variety  of  wheat,  oats,  or  other 
produce  experimented  upon  ?  It  seems  to  depend  partly  upon  both. 

a.  Variety. — ^Thus  on  the  same  field,  in  Ravensworth  Dale, 
Yorkshire,  on  a  rich  clay  soil  abounding  in  lime,  the  Golden 
Kent  and  Flanders  'Red  wheats  were  sown  in  the  spring  of  1841. 
The  former  gave  an  excellent  crop,  while  the  latter  was  a  total 
failure,  the  ear  containing  20  or  30  grains  only  of  poor  wheat. 
The  straw  of  the  former  left  165  lb.  of  ash  from  1000  lb.,  that 
of  the  latter  only  120  lb.  Something,  therefore,  depends  upon 
the  variety. 

b.  Soil. — Again,  1000  lb.  of  the  straw  of  the  same  variety  of 
oat,  grown  by  the  Messrs.  Drummond  of  Stirling  in  1841,  upon 

Aberdeen  granito,  left  96  lb.  of  ash. 

On  clay-slate,        .       18      " 


On  greenstone, 
On  limestone, 
On  gypsum, 
On  sQicious  sand, 


19 

102 

58 

64 


On  light  loamy  soil,     88 


GENERAL   CONCLUSION.  63 

Tht  quantity  of  ash,  therefore,  depends  in  some  measure  also  upon 
the  nature  of  the  soil. 

5.  Bxit  the  degree  of  ripeness  which  a  plant  has  attained  has 
also  an  influence  on  the  proportion  of  ash  which  it  leaves. 
Thus  the  straw  of  the  same  wheat  grown  on  the  same  limestone 
soil  near  Wetherby,  in  Yorkshire,  gave  me,  when  cut  five  weeks 
before  it  was  ripe,  40  lb.,  and  when  fully  ripe,  55  lb.,  from  1000 
lb.  of  dry  straw.  To  compare  the  ash,  therefore,  of  any  two 
samples  of  straw,  they  ought  to  be  gathered  in  the  same  state 
of  ripeness. 

A  similar  observation  also  has  been  made  in  regard  to  tho 
wood  of  trees.  The  quantity  of  ash  they  leave  varies  both 
with  their  age  and  with  the  season  of  the  year  at  which  they 
are  burned. 

On  the  whole,  the  truth,  so  far  as  it  can  as  yet  be  made  out, 
seems  to  be  this — that  every  plant  must  have  a  certain  quantity 
of  inorganic  matter  to  make  it  grow  in  the  most  healthy  manner 
— ^that  it  is  capable  of  living,  growing,  an(J  even  ripening  seed 
with  much  less,  and  probably  with  much  more,  than  this  quan- 
tity— but  that  those  soils  will  produce  the  most  perfect  plants 
which  can  best  supply  all  their  wants;  and  that  the  best  seed 
will  be  raised  in  those  districts  where  the  soil,  without  being 
too  rich  or  rank,  yet  can  yield  both  organic  and  inorganic  food 
in  such  proportions  as  to  maintain  the  corn  plants  in  their  most 
healthy  condition. 

This  latter  observation,  in  regard  to  the  quality  of  seed,  is 
of  great  practical  importance,  and  must  be  borne  in  mind  when 
we  come  hereafter  to  inquire  whether  seeds  can  be  so  prepared 
or  doctored,  by  steeping  or  otherwise,  as  to  grow  quicker,  with 
more  certainty,  and  with  greater  luxuriance,  and  to  yield  larger 
returns  of  grain 


64 


THE   QUALITY   OF   THE   ASH   OF   PLANTS. 


SECriON   IlL — OF  THE    COKPOSITION    OR    QUALITY   OF    THE    ASH    09 
PLANTS,  AND  THE   CIRCUMSTANCES   BY   WHICH   IT   IS   MODIFIED. 


But  much  also  depends  upon  the  quality  as  well  as  upon  the 
qxhantity  of  the  ash.  Plants  may  leave  the  same  weight  of  ash 
when  burned,  and  yet  the  nature  of  the  specimens  of  ash — the 
kind  of  matter  of  which  they  respectively  consist — ^may  be  very 
diflferent.  The  ash  of  one  may  contain  much  lime,  of  another 
much  potash,  of  a  third  much  soda,  while  in  a  fourth  much  sili- 
ca may  be  present.  Thus  100  lb.  of  the  ash  of  heart  straw  have 
been  found  to  contain  53  lb.  of  potash,  while  that  of  barley  con- 
tained only  9  lb.  in  the  hundred.  On  the  other  hand,  100  lb. 
of  the  ash  of  barley  straw  contain  68  lb.  of  silica,  while  in  that 
of  bean  straw  there  are  only  7  lb. 

The  quality  of  the  ash  seems  to  vary  with  the  same  conditions 
by  which  its  quantity  is  affected.     Thus — 

1.  It  varies  with  the  kind  of  jilant. — 1000  lb.  of  the  ash  of  the 
grain  of  wheat,  barley,  oats,  beans,  and  linseed — of  the  potato 
tuber  and  the  turnip  bulb,  for  example — contain  respectively — 


«: 

x 

Is 

d 

d. 

Potash,    . 

o 

n 

O 

Pi 

•O   o 

a 
n 

i3 

£ 

3 

237 

136 

262 

220 

;-325- 

336 

245 

557 

419 

Soda, 

91 

81 

— 

116 

106 

34 

19 

51 

Lime,       .        .        .• 

28 

26 

60 

49 

14 

58 

147 

20 

136 

Magnesia, 

120 

75 

100 

103 

162 

80 

99 

53 

53 

Oxide  of  iron,  - 

7 

15 

4 

13 

3 

6 

19 

5 

13 

Pliosphoric  acid, 

500 

390 

438 

495 

449 

380 

381 

126 

76 

Sulphuric  acid, 

3 

1 

105 

9 

28 

10 

9 

136 

136 

Silica,       » 

12 

273 

27 

4 

14 

12 

57 

42 

79 

Chlorine,  ... 

— 

trace. 

3 

— 

2 

7 

3 

42 

36 

998 

997 

999 

1009 

997 

995 

994 

10001  999 

A  comparison  of  the  numbers  in  the  first  four  columns  shows 
kow  unlike  the  quantities  of  the  different  substances  are  which 


THE   ASH   OF   6BAINS   AND   BULB.  6i> 

are  contained  in  an  equal  weight  of  the  ash  of  the  four  varieties 
of  grain.  It  is  to  be  remarked,  however,  that  the  great  differ- 
ence in  the  case  of  barley  arises  from  the  thick  husk  with  which 
it  is  covered,  and  from  which  the  large  per  centage  of  sihca  is 
derived.     The  sample  of  oats  was  taken  without  the  husk. 

Beans  contain  more  sulphuric  acid,  also,  than  any  of  the  other 
grains  in  the  above  table,  while  they  are  deficient  in  phosphoric 
acid  when  compared  with  wheat,  barley,  or  oats.  But  the  most 
striking  differences  appear  between  the  several  kinds  of  grain 
and  the  potato  and  turnip.  In  these  last  the  alkaline  matter  is 
very  much  greater,  while  the  phosphoric  acid  is  much  dimin- 
ished. 

It  is  thus  evident  that  a  crop  of  wheat  will  carry  off  from  the 
soil — even  suppose  the  whole  quantity  of  ash  left  by  each  to  be 
the  same  in  weight — very  different  quantities  of  potash,  soda, 
lime,  phosphoric  acid,  &c.,  from  what  would  be  carried  off  by  a 
crop  of  beans  or  of  potatoes.  It  will,  therefore,  exhaust  the  soil 
more  of  some,  as  beans  and  potatoes  will  of  other  substances. 
Hence  one  reason  why  a  piece  of  land  may  suit  one  crop  and  not 
suit  another.  Hence,  also,  two  successive  crops  of  different 
kinds  may  groAv  well  where  it  would  greatly  injure  the  soil  to 
take  two  in  succession  of  the  same  kind,  especially  of  either 
wheat  or  barley  :  and  hence  we  likewise  deduce  one  natural  rea- 
son for  a  rotation  of  crops.  The  surface-soil  may  be  so  far  ex- 
hausted of  one  inorganic  substance  that  it  cannot  afford  it  in 
sufficient  quantity  to  bring  a  given  crop  to  healthy  maturity  ; 
and  yet  this  substance  may,  by  natural  processes,  be  so  far  re- 
stored again,  during  the  intermediate  growth  of  certain  other 
crops,  as  to  be  prepared  in  a  future  season  fully  to  supply  all 
the  wants  of  the  same  crop,  and  to  yield  a  plentiful  harvest. 

2.  The  kind  of  inorganic  matter  varies  with  the  part  of  the 
flant. — Thus  the  grain  and  the  straw  of  the  corn-plants  contain 
very  unlike  quantities  of  the  several  inorganic  constituents,  as 
will  appear  by  comparing  the  several  columns  in  the  following 
with  those  of  the  preceding  table. 


66 


ASH   OF    STRAW, 


1000  lb.  of  the  ash  of  the  straw  of  wheat,  barley,  oats,  rye, 
and  Indian  corn,  have  been  found  to  contain  respectively  of — 


Potash,  -    .    - 

Wheat 

Barley. 

Oats. 

Rye. 

Indian 
corn. 

125 

92 

191 

173 

96 

Soda,      .    -    - 

2 

3 

97 

3 

286 

Lime,      -    -    - 

67 

85 

81 

90 

83 

Magnesia,    -    - 

39 

50 

38 

24 

66 

Oxide  of  iron,  - 

13 

10 

18 

14 

8 

Phosphoric  acid, 

31 

31 

26 

38 

171 

Sulphuric  acid,- 

58 

10 

33 

8 

7 

Chlorine,     -    - 

11 

6 

32 

5 

15 

Silica,     -    -    - 

654 

676 

484 

645 

270 

1000 

963 

1000 

1000 

1012 

The  quantities  of  the  several  inorganic  substances  contained 
in  the  above  kinds  of  straw  are  very  different  from  those  con- 
tained in  the  corresponding  kinds  of  grain.  In  this  difference 
we  see  ont  reason  why  the  same  soil  which  may  be  favorable  to 
the  growth  of  the  straw  of  the  corn  plant  may  not  be  equally 
propitious  to  the  growth  of  the  ear.  The  straw  contains  com- 
paratively little  of  some  of  the  ingredients  found  in  the  ear,  es- 
pecially of  the  lime,  magnesia,  and  phosphoric  acid,  while  the 
grain  contains  a  large  proportion  of  these  substances.  On  the 
other  hand,  the  straw  is  rich,  and  the  grain  very  poor  in  silica. 
It  is  clear,  therefore,  that  the  roots  may,  in  certain  plants  and 
in  certain  soils,  succeed  in  fully  nourishing  the  straw,  while  they 
cannot  fully  ripen  the  ear  ;  or  contrariwise,  where  they  feed  but 
a  scanty  straw,  may  yet  he  able  to  give  ample  sustenance  to  the 
filling  ear.* 

That  similar  differences  prevail  in  other  orders  of  plants  also, 
and  that  their  several  parts  require,  therefore,  different  propor- 

*  And  occasionally  do  give ;  for  a  plump  grain,  and  even  a  well-filled  ear, 
are  not  un frequently  found  where  the  straw  is  unusually  deficient 


ASH    OF  THE   APPLE   TREE   AND   FRUIT. 


67 


tions  of  the  several  kinds  of  inorganic  food  to  bring  them  to 
perfection,  is  shown  by  the  following  table. 

1000  lb.  of  the  ash  of  the  stem,  leaves,  and  fruit  of  the  apple 
tree,  {Pyrus  spectabilis — Chinese  crab,)  have  been  found  to 
C0D.tain  respectively,  (Vogel,) 


Carbonates  of  potash  and  soda, 
Phosphates  of  do.,  -        -        - 
Carbonate  of  lime,  -        -        - 
Carbonate  of  magnesia,  - 
Phosphates  of  Uine  and  magnesia, 
Silica, 

Stem. 

Loaves 

Fruit. 

46 

822 
49 
88 

68 

trace. 

729 

98 
105 

190 
141 
370 

55 
186 

37 

1005 

1000 

979 

Thus  potash  and  phosphoric  acid  abound  most  in  the  fruit 
of  the  apple  tree,  as  they  do  in  the  ear  of  our  corn  plants,  and 
are  therefore  as  necessary  to  their  healthy  growth  and  complete 
maturity, 

3.  The  quality  of  the  ask  varies  also  with  the  kind  of  soil  in 
which  the  pl<int  is  made  to  grow. — This  will  be  understood  from 
what  has  been  stated  above.  Where  the  soil  is  favorable,  the 
foots  can  send  up  into  the  straw  everything  which  the  plant  re- 
quires for  its  healthy  growth,  and  in  the  right  proportions. 
When  it  is  either  too  poorly  or  too  richly  supplied  with  one  or 
more  of  those  inorganic  constituents  which  the  plant  desires, 
life  may  indeed  be  prolonged,  but  a  stunted  or  unhealthy  crop 
will  be  raised,  and  the  kind,  and  perhaps  the  quantity,  of  ash 
left  on  burning  it,  will  necessarily  be  different  from  that  left  by 
the  same  species  of  plant  grown  under  more  favoring  circum- 
stances. Of  this  fact  there  can  be  no  doubt,  though  the  extent 
to  which  such  variations  may  take  place  without  a'hsolutely  kill- 
ing the  plant  has  not  yet  been  made  out.  That  it  is  considera- 
ble is  shown  by  the  following  table,  which  exhibits  the  compo- 


68 


INFLUENCE  OP   SOILAGE  AND   SEASON, 


rition  of  1000  lb.  of  the  ash  of  three  samples  of  wheat  grown  it 
diflferent  localities  : — 


Dutch. 

German. 

White. 

Red. 

Potash,  . 
Soda,      . 
Lime, 
Magnesia, 
Oxide  of  iron, 
Sulphuric  acid. 
Phosphoric  acid, 
SUica,     . 

64 

278 

39 

130 

5 

3 

461 

3 

219 

157 

19 

96 

14 

2 

493 

338 

31 

136 

3 

492 

983 

1000 

1000 

In  the  first  of  these  we  find  little  potash,  in  the  last  no  soda, 
while  in  all  nearly  half  the  weight  consists  of  phosphoric  acid. 

4.  It  varies  also  with  the  period  of  the  plant's  growth,  or  the 
season  at  which  it  is  reaped. — ^Thus,  in  the  young  leaf  of  the 
turnip  and  potato,  a  greater  proportion  of  the  inorganic  matter 
consists  of  potash  than  in  the  old  leaf.  The  same  is  true  of  the 
stalk  of  wheat;  and  similar  differences  prevail  in  almost  every 
kind  of  plant  at  different  stages  of  its  growth. 

The  enlightened  agriculturist  will  perceive  that  all  the  facts 
above  stated  have  a  more  or  less  obvious  connection  with  the 
ordinary  processes  of  practical  agriculture,  and  tend  to  throw 
considerable  light  on  some  of  the  principles  by  which  these  pro- 
cesses ought  to  be  regulated.  One  illustration  of  this  is  exhib- 
ited in  the  following  section. 


SECTION  IV. AVERAGE   QUANTriY  OF  INORGANIC  MATTER  CONTAINED 

IN   AN    ORDINARY    CROP,    OR   SERIES    OF    CROPS. 

The  importance  of  the  inorganic  matter  contained  in  living 
vegetables,  or  in  vegetable  substances  when  reaped  and  dry, 


WHAT   A   WHOLE   CROP   CARRIES   OFF. 


69 


will  appear  more  distinctly  if  we  consider  the  actual  quantity 
carried  off  from  the  soil  in  the  series  of  crops. 

In  a  four  years'  course  of  cropping,  in  which  the  crops  gathered 
amounted  per  acre  to — 

1st  year,  Turnips,  20  tons  of  bulbs  and  6;^  tons  of  tops. 

2d  year,  Barley,  4jO  bushels  of  63  lb.  each,  and  1  ton  of  straw. 

3d  year.  Clover  and  Rye- Grass,  \h  ton  of  each  in  hay. 

4th  year,  Wlieat,  25  bushels  of  60  lb.,  and  1|  tons  of  straw. 

1°.  The  quantity  of  inorganic  matter  carried  off  in  the  four 
crops,  supposing  none  of  them  to  be  eaten  on  the  land,  amounts 
to  about — 


Potaali, 

317  lb. 

Sulphuric  acid,     . 

108  lb. 

Soda^ 

54  " 

Phosphoric  acid 

116  " 

Lime,  .        . 

193  " 

Chlorine,     . 

70  " 

Magnesia^    . 

55  " 

Oxide  of  iron, 

15  " 

SUicaj 

356  " 

Total, 

1284  ' 

or  in  all  about  11  cwt.;  of  which  gross  weight  the  different  sub- 
stances form  unlike  propertions. 

2°.  A  still  clearer  view  of  these  quantities  will  be  obtained  by 
a  consideration  of  the  fact,  that  if  we  carry  off  the  entire  pro- 
duce, and  add  none  of  it  again  in  the  shape  of  manure,  we  must 
or  ought,  in  its  stead,  if  the  land  is  to  be  restored  to  its  original 
condition,  to  add  to  each  acre  every  four  years — 


Dry  pearl-ash, 
Coan*non  bone  dust, 
Epsom  salts. 
Common-salt, 
Quick-lime,    . 

Total, 


465  lb, 
552  " 
326  " 
116  " 
70  « 

1529  " 


Several  observations  suggest  themselves  from  a  consideration 
of  the  above  statements. 

First,  That  if  this  inorganic  matter  be  really  necessary  to  the 
plant,  the  gradual  and  constant  removal  of  it  from  the  land 
ought,  by  and  by,  to  make  the  soil  poorer  in  this  part  of  the 
food  of  plants. 


70  GENERAL  CONSIDERATIONS. 

Second,  That  the  more  of  the  crops  which  grows  npon  the 
land  we  return  to  it  again  in  the  form  of  manure,  the  less  wij 
this  deterioration  be  perceptible. 

Third,  That  as  many  of  these  inorganic  substances — the 
potash,  soda,  &c., — are  readily  soluble  in  water,  the  liquid  ma- 
nure of  the  farmyard,  so  often  allowed  to  run  to  waste,  must 
carry  with  it  to  the  rivers  much  of  the  saline  matter  that  ought 
to  be  returned  to  the  land. 

Fourth,  If  the  rains  also  are  allowed  to  run  over  and  wash 
the  surface  of  the  soil,  they  will  gradually  deprive  it  of  those 
soluble  saline  substances  which  appear  to  be  so  necessary  to  the 
growth  of  plants.  Hence  one  important  benefit  of  a  system  of 
drainage  so  perfect  as  to  allow  the  rains  to  sink  into  the  soil 
where  they  fall,  and  thus  to  carry  down,  instead  of  away,  what 
they  naturally  dissolve. 

And,  lastly,  That  the  utility,  and  often  indispensable  necessity, 
of  certain  artificial  manures — though,  in  some  districts,  perhaps 
arising  from  the  natural  poverty  of  the  land  in  some  of  the 
mineral  substances  which  plants  require — ^is  most  frequently 
owing  to  a  want  of  acquaintance  with  the  facts  above  stated, 
and  to  the  long-continued  neglect  and  waste  which  has  been  the 
natural  consequence. 

In  certain  districts,  the  soil  and  subsoil  contain  within  them- 
selves an  almost  unfailing  supply  of  some  of  these  inorganic  or 
mineral  substances,  so  that  the  waste  of  them  is  long  in  being  felt; 
in  others,  again,  the  land  contains  less,  and  therefore  becomes 
sooner  exhausted.  This  latter  class  of  soils  requires  a  more 
careful,  and  usually  a  more  expensive  mode  of  cultivation  than 
the  first;  but  both  will  become  at  length  alike  unproductive,  if 
that  which  is  yearly  taken  from  the  soil  is  not  in  s«me  form  or 
other  restored  to  it. 

One  thing  is  of  essential  importance  to  be  remembered  by  the 
practical  farmer — that  the  deterioration  of  land  is  often  an  ex- 
ceedingly slow  process.  In  the  hands  of  successive  generations, 
a  field  may  so  imperceptibly  become  less  valuable,  that  a  cea 


ARTIFICIAL  MANURES,    WHT   NECESSARY  7 

tory  even  may  elapse  before  the  change  prove  such  as  to  make 
a  sensible  diminution  in  the  valued  rental.  Such  slow  changes, 
however,  have  been  seldom  recorded;  and  hence  the  practical 
man  is  occasionally  led  to  despise  the  clearest  theoretical  prin- 
ciples, because  he  has  not  happened  to  see  them  verified  in  his 
own  limited  experience;  and  to  neglect,  therefore,  the  sug- 
gestions and  the  wise  precautions  which  these  principles  lay 
before  him. 

The  special  agricultural  history  of  known  tracts  of  land  of 
different  qualities,  showing  how  they  had  been  cropped  and  tilled, 
and  the  average  produce  in  grain,  hay,  and  stock  every  five 
years,  during  an  entire  century,  would  afford  invaluable  mate- 
rials both  to  theoretical  and  to  practical  agriculture. 

General  illustrations  of  this  sure  though  slow  decay  may  be 
met  with  in  the  agricultural  history  of  almost  every  country. 
In  none,  perhaps,  are  they  more  striking  than  in  the  older  slave 
states  of  North  America.  Maryland,  Yirginia,  and  North  Ca- 
rolina— once  rich  and  fertile — by  a  long-continued  system  of 
forced  and  exhausting  culture,  have  become  unproductive  in 
many  places,  and  vast  tracts  have  been  abandoned  to  appa- 
rently hopeless  sterility.  Such  lands  it  is  possible  to  reclaim, 
but  at  what  an  expense  of  tune,  labor,  manure,  and  skilful 
management  I  It  is  to  be  hoped  that  the  newer  states  will 
not  thus  sacrifice  their  future  power  and  prospects  to  present 
and  temporary  wealth — that  the  fine  lands  of  Ohio,  Kentucky, 
and  the  Prairie  states,  which  now  yield  Indian  corn  and  wheat, 
crop  after  crop,  without  intermission  and  without  manure,  will 
not  be  so  cropped  till  their  strength  and  substance  is  gone,  but 
that  a  better  conducted  and  more  skilful  husbandry  will  con- 
tinue, withmit  diminishing  the  present  crops,  to  secure  a  per- 
manent fertility  to  that  naturally  rich  and  productive  country. 

SECTION  V. PRACTICAL  DEDUCTIONS   TO    BE   DRAWN   FROM  A   KNOW- 
LEDGE OF  THE  INORGANIC  CONSTITUENTS  OF  PLANTS, 

Several  important  practical  deductions  are  to  be  drawn  from 


18  PRACTICAL  DEDUCTIONS. 

what  has  been  stated  in  regard  to  the  inorganic  constituents  of 
plants. 

1'^.  Why  one  crop  may  grow  well  where  another  fails. — Sup- 
pose, for  example,  a  crop  to  require  a  peculiarly  large  supply 
of  potash — it  may  grow  well  if  the  soil  abound  in  potash  ;  but 
if  the  soil  be  deficient  in  potash  and  abound  in  lime,  then  this 
crop  may  scarcely  grow  at  all  upon  it,  while  another  crop  to 
which  lime  is  especially  necessary  may  grow  luxuriantly. 

2°.  Why  mixed  crops  grow  well  togdher. — If  two  crops  of 
unlike  kinds  be  sown  together,  their  roots  suck  in  the  inorganic 
substances  in  diflferent  proportions — the  one  more  potash  and 
phosphoric  acid  perhaps — ^^e  other  more  lime,  magnesia,  or 
silica.  They  thus  interfere  less  with  each  other  than  plants  of 
the  same  kind  do — which  require  the  same  kinds  of  food  in 
nearly  the  same  proportions. 

Or  the  two  kinds  of  crop  grow  with  different  degrees  of 
rapidity,  or  at  different  periods  of  the  year  ;  and  thus,  while 
the  roots  of  the  one  are  busy  drawing  in  supplies  of  inorganic 
nourishment,  those  of  the  other  are  comparatively  idle  ;  and 
thus  the  soil  is  able  abundantly  to  supply  the  wants  of  each  as 
its  time  of  need  arrives. 

3°.  Why  the  same  crop  grows  letter  on  the  same  soil  after  long 
intervals. — If  each  crop  demands  special  substances,  or  these 
substances  in  quantities  peculiar  to  itself,  or  in  some  peculiar 
state  of  combination,  the  chances  that  the  soil  will  be  able  to 
supply  them  are  greater,  the  more  distant  the  intervals  at 
which  the  same  crop  is  grown  upon  it.  Other  crops  do  not 
demand  the  same  substances,  or  in  the  same  proportions  ;  and 
thus  they  may  gradually  accumulate  on  the  soil  till  it  becomes 
especially  favorable  to  the  particular  crop  we  wish  to  grow. 

4°.  Why  a  rotation  of  crops  is  necessary. — Suppose  the  soil 
to  contain  a  certain  average  supply  of  all  those  inorganic  sub- 
stances which  plants  require,  and  that  the  same  corn  crop  is 
grown  upon  it  for  a  long  series  of  years — this  crop  will  carry 
off  some  of  these  substances  in  larger  proportion  than  others, 


ROTATION    OF    CROPS  :    EXHAUSTION.  73 

SO  that  year  by  year  the  quantity  of  those  which  are  thus 
chiefly  carried  off  will  become  relatively  less.  Thus  at  length 
the  soil,  for  want  of  these  special  substances,  will  become 
unable  to  bear  a  corn  crop  at  all,  though  it  may  still  contain  a 
large  store  of  the  other  inorganic  substances  which  the  corn 
crop  does  not  specially  exhaust.  Suppose  bean  or  turnip  crops 
raised  in  like  manner  for  a  succession  of  years,  they  would 
exhaust  the  soil  of  a  different  set  of  substances  till  it  became 
unable  to  grow  them  profitably,  though  still  rich  perhaps  iu 
those  things  which  the  corn  crop  especially  demands. 

But  grow  these  crops  alternately,  then  the  one  crop  will 
draw  especially  upon  one  class  of  substances,  the  other  crop 
upon  another  ;  and  thus  much  larger  crops  of  each  will  be 
reaped  from  the  same  soil,  and  for  a  much  longer  period  oi 
time. 

On  this  principle  the  benefit  of  a  rotation  of  crops  iu  an 
important  degree  depends.* 

5°.  WTiat  is  meant  by  exhmcstion. — ^Thus,  exhaustion  may 
either  be  general,  arising  from  the  gradual  carrying  off  of  all  the 
kinds  of  food  on  which  plants  live — or  special,  arising  from  the 
want  of  one  or  more  of  those  substances  which  the  crops  that 
have  been  long  grown  upon  it  have  specially  required. 

To  repair  the  former  kind  of  exhaustion,  an  addition  of 
many  things  to  the  soil  may  be  necessary  ; — to  repair  the 
latter,  it  may  be  sufficient  to  add  a  needful  supply  of  one 
or  more  things  only.  In  showing  how  this  may  be  most 
efficiently  and  most  economically  done,  chemistry  will  be  of 
tho  most  essential  service  to  the  practical  man.  Before  en- 
tering further  upon  this  point,  however,  it  will  be  necessary  to 
study  also  the  nature  of  the  soil  in  which  plants  grow. 

*  In  showing,  in  the  above  remarks,  how  the  doctrine  of  the  inorganic 
part  of  plants  throws  hght,  among  other  things,  upon  the  use  of  a  rotation 
of  crops,  the  reader  will  bear  in  mind  that  a  knowledge  of  the  organic  por- 
tion of  the  plant,  and  of  the  living  functions  of  each  part  in  each  species,  is 
no  less  necessary  to  the  full  understanding  of  this  intricate  subject. 
4 


CHAPTER  V. 

Of  Boils. — Their  organic  and  inorganic  portions. — Saline  or  soluble,  and 
earthy  or  insoluble,  matter  in  soils. — Examination  and  classification  of 
soils. — Determination  of  the  per-centage  of  sand,  clay,  vegetable  matter, 
and  lime. — Diversities  of  soils  and  subsoils. 

Soils  consist  of  two  parts  ;  of  an  organic  part,  which  can 
readily  be  burned  away  when  the  soil  is  heated  to  redness  ;  and 
of  an  iriorganic  part,  which  is  fixed  in  the  fire,  and  which  con- 
sists entirely  of  earthy  and  saline  substances. 

SECTION   I. OF   THE   ORGANIC   PART   OF   SOILS. 

The  organic  part  of  soils  is  derived  chiefly  from  the  remains 
of  vegetables  and  animals  which  have  lived  and  died  in  or  npou 
the  soil,  which  have  been  spread  over  it  by  rivers  and  rains  ;  oi 
which  have  been  added  by  the  hands  of  man,  for  the  purpose 
of  increasing  its  natural  fertility. 

This  organic  part  varies  very  much  in  quantity  in  different 
soils.  In  some,  as  in  peaty  soils,  it  forms  from  50  to  70  per 
cent  of  their  whole  weight ;  and  even  in  rich  long-cultivated 
soils  it  has  been  found,  in  a  few  rare  cases,  to  amount  to  as 
much  as  25  per  cent.  In  general,  however,  it  is  present  in 
much  smaller  proportion,  even  in  our  best  arable  lands.  Oats 
and  rye  will  grow  upon  a  soil  containing  only  1  \  per  cent,  barley 
when  2  to  3  per  cent  are  present,  while  good  wheat  soils  gene- 
rally contain  from  4  to  8  per  cent.  The  rich  alluvial  soil  of  the 
valley  of  the  Nile  contains  only  5  per  cent  of  dry  organic  mat- 
ter. In  stiff  and  very  clayey  soils,  10  to  12  per  cent  is  some- 
times found.  In  very  old  pasture-lands,  and  in  gardens,  vegeta- 
ble matter  occasionally  accumulates  so  as  to  overload  the  upper 
soil. 


ORGANIC   AND   INOBGANIC   PARTS   OF  THE  SOIL.  T» 

To  this  organic  matter  in  the  soil  the  name  of  humus  has 
been  given  by  some  writers.  It  contains,  or  yields  to  the  plant, 
the  ulmic,  humic,  and  other  acids  already  described,  (see  Chap- 
ter II.)  It  supplies  also,  by  its  decay  in  contact  with  the  air 
which  penetrates  the  soil,  much  carbonic  acid,  which  is  supposed 
to  enter  the  roots,  and  thus  to  assist  the  growth  of  living  vege- 
tables. During  the  same  decay,  ammonia,  as  we  have  already 
stated,  is  likewise  produced,  and  this  in  larger  quantity  if  ani- 
mal matter  be  present  in  considerable  abundance.  Other  sub- 
stances, more  or  less  nutritious,  are  also  formed  from  the  organic 
matter  in  the  soil.  These  enter  by  the  roots,  and  contribute  to 
nourish  the  growing  plant,  though  the  extent  to  which  it  is  fed 
from  this  source  is  dependent,  both  upon  the  abundance  witk 
which  these  substances  are  supplied,  and  upon  the  nature  of  the 
plant  itself,  and  of  the  climate  in  which  it  grows. 

Another  influence  of  this  organic  portion  of  the  soil,  whether 
naturally  formed  in  it  or  added  to  it  as  manure,  is  not  to  be 
neglected.  It  contains — as  all  vegetable  substances  do— ^a  con« 
siderable  quantity  of  inorganic,  that  is,  of  saline  and  earthy 
matter,  which  is  liberated  as  the  organic  part  decays.  Thus 
living  plants  derive  from  the  remains  of  former  races,  buried 
beneath  the  surface,  a  portion  of  that  inorganic  food  which  can 
only  be  obtained  from  the  soil,  and  which,  if  not  thus  directly 
supplied,  must  be  sought  for  by  the  slow  extension  of  their  roots 
through  a  greater  depth  and  breadth  of  the  earth  in  which  thej 
grow.  The  addition  of  manure  to  the  soil,  therefore,  places 
within  the  easy  reach  of  the  roots  not  only  organic  but  also  ihor- 
ganic  food. 

SECTION   II. OF  THE   INORGANIC   PART   OF   SOILS. 

The  inorganic  part  of  soils — that  which  remains  behind,  when 
everything  combustible  is  burned  away  by  heating  it  to  redness 
in  the  open  air — consists  of  two  portions,  one  of  which  is  sduhh 
in  water,  the  other  insoluble.  The  soluble  consists  of  saline  sub- 
stances, the  insoluble  of  earthy  substances. 


t9  SALINE  OR  SOLUBLE  PART. 

1.  7%e  saltnt  or  soluble  portion. — In  this  country,  the  surface- 
soil  of  our  fields,  in  general,  contains  very  little  soluble  matter. 
If  a  quantity  of  soil  be  dried  in  an  oven,  a  pound  weight  of  it 
taken,  and  a  pint  and  a-half  of  pure  boiling  rain  water  poured 
over  it,  and  the  whole  well  stirred  and  allowed  to  settle,  the 
clear  liquid,  when  poured  off  and  boiled  to  dryness,  may  leave 
from  30  to  100  grains  of  saline  mixed  with  a  variable  quantity 
of  organic  matter.  This  saline  matter  will  consist  of  common 
salt,  gypsum,  sulphate  of  soda,  (Glauber's  salts,)  sulphate  of 
magnesia,  (Epsom  salts,)  with  traces  of  the  chlorides  of  calcium, 
magnesium,  and  potassium,  and  of  potash,  soda,  lime,  and  mag- 
nesia, in  combination  with  nitric  and  phosphoric,  and  with  the 
humic  and  other  organic  acids.  It  is  from  these  soluble  sub- 
stances that  the  plants  derive  the  greater  portion  of  the  saline 
ingredients  contained  in  the  ash  they  leave  when  burned. 

Nor  must  the  quantity  thus  obtained  from  a  soil  be  considered 
too  small  to  yield  the  whole  supply  which  a  crop  requires.  A 
single  grain  of  saline  matter  in  every  pound  of  a  soil  a  foot  dejep, 
is  equal  to  600  lb.  in  an  acre.  This  is  more  than  is  carried  off 
from  the  soil  in  ten  rotations,  (forty  years,)  where  only  the 
wheat  and  barley  are  sent  to  market,  and  the  straw  and  green 
crops  are  regularly,  and  without  loss,  returned  to  the  land  in 
the  manure.* 

In  some  countries — indeed,  in  some  districts  of  our  own  coun- 
try— the  quantity  of  saline  matter  in  the  soil  is  so  great  as  in 
hot  seasons  to  form  a  white  incrustation  on  the  surface.  It  may 
often  be  seen  in  the  neighborhood  of  Durham  ;  and  is  more 
especially  to  be  looked  for  in  districts  where  the  subsoil  is  sandy 
and  porous,  and  more  or  less  full  of  water.  In  hot  weather, 
the  evaporation  on  the  surface  causes  the  water  to  ascend  from 
the  porous  subsoil ;  and  as  this  water  always  brings  with  it  a 
quantity  of  saline  matter,  which  it  leaves  behind  when  it  rises 

*  A  further  portion,  it  will  be  recollected,  is  carried  off  iu  the  cattle  that 
are  sent  to  market,  or  ia  lost  in  the  liquid  manure  that  is  wasted,  or  is  washed 
out  by  the  rains  from  the  soil  or  from  the  manure ;  all  these  are  here  neglected. 


SALINE   INCRUSTATIONS  UPON  THE   SOIL,  77 

fii  vapor,  it  is  evident  that,  the  longer  the  dry  weather  aid 
consequent  evaporation  from  the  surface  continue,  the  thicker 
the  incrustations  will  be,  or  the  greater  the  accumulations  of 
saline  matter  on  the  surface.  Hence,  where  such  a  moist  and 
porous  subsoil  exists  in  countries  rarely  visited  by  rain,  as  in  the 
plains  of  Peru,  of  Egypt,  or  of  India,  the  country  is  whitened 
over  in  the  dry  season  with  an  unbroken  snowy  covering  of  the 
different  saline  substances  above  mentioned. 

When  rain  falls,  the  saline  matter  is  dissolved,  and  descends 
again  to  the  subsoil.  In  dry  weather  it  re-ascends.  Hence  the 
surface-soil  of  any  field  will  contain  a  larger  proportion  of  solu- 
ble inorganic  matter  in  the  middle  of  a  hot  dry  season  than  in 
one  of  even  ordinary  rain.  Hence,  also,  the  fine  dry  weather 
which,  in  early  summer,  hastens  the  growth  of  corn,  and  later 
in  the  season  favors  its  ripening,  does  so  probably,  among  its 
other  modes  of  action,  by  bringing  up  to  the  roots  from  beneath 
a  more  ready  supply  of  those  saline  compounds  which  the  crop 
requires  for  its  healthful  growth.  In  some  countries,  however, 
this  saline  matter  ascends  in  such  quantity  as  to  render  the  soil 
unfit  to  grow  the  more  tender  crops.  Thus,  on  the  plains  of 
Attica,  when  the  rainy  season  ends,  saline  substances  begin  to 
rise  to  the  surface  in  such  abundance  as  by  degrees  entirely  to 
burn  up  or  prevent  the  growth  of  grass,  though  abundant  wheat 
crops  are  yearly  ripened. 

2.  The  earthy  or  insoluble  portion. — ^The  earthy  or  insoluble 
portion  of  soils  rarely  constitutes  less  than  95  lb.  in  a  hundred 
of  their  whole  weight.  It  consists  chiefly  of  silica  in  the  form 
of  sand — of  alumina  mixed  or  combined  with  silica  in  the  form 
of  clay — and  of  lime  in  the  form  of  carbonate  of  lime.  It  is 
rarely  free,  however,  from  two  or  three  per  cent  of  oxide  of 
iron  ;  and  where  the  soil  is  of  a  red  color,  this  oxide  is  often 
present  in  still  larger  proportion.  A  trace  of  magnesia  also 
may  be  almost  always  detected,  and  a  minute  quantity  of  phos- 
phate of  lime.  The  principal  ingredients,  however,  of  the 
earthy  part  of  all  soils  are  sand,  clay,  and  lime  ;  and  soils  are 


78  SEPARATION  07  SAKD  AND  CLAT. 

named  or  classified  according  to  the  quantity  of  each  of  these 
three  they  may  happen  to  contain. 

a.  If  an  ounce  of  soil  be  intimately  mixed  with  a  pint  ol 
water  till  it  is  perfectly  softened  and  diffused  through  it,  and 
if,  after  shaking,  the  heavy  parts  be  allowed  to  settle  for  a  few 
minutes,  the  sand  will  subside,  while  the  clay,  which  is  in  finer 
particles,  and  is  less  heavy — will  still  remain  floating.  If  the 
water  and  fine  floating  clay  be  now  poured  into  another  vessel, 
and  be  allowed  to  stand  till  the  water  has  become  clear,  the 
sandy  part  of  the  soil  will  be  found  on  the  bottom  of  the  first 
vessel,  and  the  clayey  part  on  that  of  the  second,  and  they 
may  be  dried  and  weighed  separately. 

h.  If  100  grains  of  dry  soil,  not  peaty  or  unusually  rich  in 
vegetable  matter,  leave  no  more  than  10  of  clay  when  treated 
in  this  manner,  it  is  called  a  saiidy  soil;  if  from  10  to  40,  a 
sandy  loam  ;  if  from  40  to  10,  a  loamy  soil;  if  from  10  to  85,  a 
day  loam  ;  from  85  to  95,  a  strong  day  soil ;  and  when  no  sand 
is  separated  at  all  by  this  process,  it  is  a  pure  agricultural  day. 

c.  The  strong  day  soils  are  such  as  are  used  for  making  tiles 
and  bricks  ;  the  pure  agricultural  day  is  such  as  is  commonly 
employed  for  the  manufacture  of  pipes,  (pipe-clay.)  This  pure 
clay  is  a  chemical  compound  of  silica  and  alumina,  in  the  pro- 
portion of  about  60  of  the  former  to  40  of  the  latter.  Soils 
of  pure  clay  rarely  occur — ^it  being  well  known  to  all  practical 
men  that  the  strong  clays,  (tile  clays,)  which  contain  from  5 
to  15  per  cent  of  sand,  are  brought  into  arable  cultivation 
with  the  greatest  possible  difficulty.  It  will  rarely,  almost 
never,  happen,  therefore,  that  arable  land  will  contain  more 
than  30  to  35  per  cent  of  alumiaa. 

d.  If  a  soil  contain  more  than  5  per  cent  of  carbonate  of 
lime,  it  is  called  a  marl;  if  more  than  20  per  cent,  it  is  a  cal- 
careous soil.  JPeaty  soils,  of  course,  are  those  in  which  the 
vegetable  matter  predominates  very  much. 

e.  The  quantity  of  vegetable  or  other  organic  matter  is  de- 
termined by  drying  the  soil  wdl  upon  paper  in  an  oven,  until  ii 


DIVERSITIES    OF   SOILS   AND   SUBSOILS.  79 

ceases  to  lose  weight — taking  care  that  the  heat  is  not  so  great 
as  to  char  the  paper — and  then  burning  in  the  open  air  a 
weighed  quantity  of  the  dried  soil  :  the  loss  by  burning  is 
nearly  all  organic  matter.  In  stiff  clays  this  loss  will  include 
also  a  portion  of  water,  which  is  not  wholly  driven  off  from 
such  soils  by  drying  upon  paper  in  the  way  described. 

/.  To  estimate  the  lime,  a  quantity  of  the  soil  should  be 
heated  in  the  air  till  the  organic  matter  is  burned  away.  A 
weighed  portion,  (200  or  300  grains,)  should  then  be  diffused 
through  half  a  pint  of  cold  watet  mixed  with  half  a  wine- 
glassful  of  spirit  of  salt,  (muriatic  acid,)  and  allowed  to  stand 
for  a  few  hours,  with  occasional  stirring.  When  minute  bub- 
bles of  gas  cease  to  rise  from  the  soil,  the  water  is  poured  off, 
the  soil  dried,  heated  to  redness  as  before,  and  weighed  :  the 
loss  is  nearly  all  lime. 

SECTION    III. — OF   THE   DIVERSITIES    OF   SOILS   AND    SUBSOILS. 

1st.  Soils. — ^Though  the  substances  of  which  soils  chiefly  con- 
Bist  are  so  few  in  number,  yet  every  practical  man  knows  how 
very  diversified  they  are  in  character — ^how  very  different  in 
agricultural  value.  Thus,  in  some  of  our  southern  counties, 
we  have  a  white  soil,  consisting  apparently  of  nothing  else  but 
chalk  ;  in  the  centre  of  England  a  wide  plain  of  dark-red 
land  ;  in  the  border  counties  of  Wales,  and  on  many  of  our 
coal-fields,  tracts  of  country  almost  perfectly  black  ;  while 
yellow,  white,  and  brown  sands  and  clays  give  the  prevailing 
character  to  the  soils  of  other  districts.  Such  differences  as 
these  arise  from  the  different  proportions  in  which  the  sand, 
lime,  clay,  and  the  oxide  of  iron  and  organic  matter  which 
color  the  soils,  have  been  mixed  together. 

But  how  have  they  been  so  mixed — differently  in  different 
parts  of  the  country  ?  By  what  natural  agency  ?  For  what 
end? 

2d.  Subsoil. — Again,  the  surface-soil  rests  on  what  is  usually 
denominated  the  subsoil.     This  is  also  very  variable  in  its  cha- 


80  IMPORTANCE  OF  THE  SUBSOIL. 

racter  and  quality.  Sometimes  it  is  a  porous  sand  or  gravel, 
through  which  water  readily  ascends  from  beneath,  or  sinks  in 
from  above  ;  sometimes  it  is  light  and  loamy,  like  the  soil  that 
rests  upon  it  ;  sometimes  stiff,  and  more  or  less  impervious 
to  water. 

The  most  ignorant  farmer  knows  how  much  the  value  of  a 
piece  of  land  depends  upon  the  character  of  the  surface-soil, — 
the  intelligent  improver  understands  best  the  importance  of  a 
favorable  subsoil.  "  When  I  came  to  look  at  this  farm,"  said 
an  excellent  agriculturist  to  me,  "  it  was  spring,  and  damp, 
growing  weather  :  the  grass  was  beautifully  green,  the  clover 
shooting  up  strong  and  healthy,  and  the  whole  farm  had  the 
appearance  of  being  very  good  land.  Had  I  come  in  June, 
when  the  heat  had  drunk  up  nearly  all  the  moisture  which  the 
saTidy  subsoil  had  left  on  the  surface,  I  should  not  have  offered 
so  much  rent  for  it  by  ten  shillings  an  acre."  He  might  have 
said  also,  "  Had  I  taken  a  spade,  and  dug  down  18  inches  in 
various  parts  of  the  farm,  I  should  have  known  what  to  expect 
in  seasons  of  drought." 

But  how  come  subsoils  thus  to  differ — one  from  the  other — 
and  from  the  surface-soil  that  rests  upon  them  ?  Are  there 
any  principles  by  which  such  differences  can  be  accounted  for — 
by  which  they  can  be  foreseen — by  the  aid  of  which  we  can 
tell  what  kind  of  soil  may  be  expected  in  this  or  that  district, 
even  without  visiting  the  spot,  and  on  what  kind  of  subsoil  it 
is  likely  to  rest  ? 

Geology  explains  the  cause  of  many  of  these  differences, 
and  supplies  us  with  principles  by  which  we  can  predict  the 
general  quality  of  both  soils  and  subsoils  in  the  several  parts 
of  entire  kingdoms  ;  and  where  the  soil  is  of  inferior  quality, 
and  yet  susceptible  of  improvement,  the  same  principles  indi- 
cate whether  the  means  of  improving  it  are  likely  to  exist  in 
any  given  locality,  or  to  be  attainable  at  a  reasonable  cost. 

It  will  be  proper  shortly  to  illustrate  these  direct  relations  of 
geology  to  agriculture. 


CHAPTER  yi. 

Direct  relations  of  geology  to  agriculture. — Origin  of  soils. — Causes  of  their 
diversity. — Relation  of  soils  to  the  rocks  on  which  they  rest. — Constancy 
in  the  relative  position  and  character  of  the  stratified  rocks. — Relation  of 
this  fact  to  practical  agriculture. — Of  primary,  secondary,  tertiary,  and 
post-tertiary  rocks. — Different  soils  observed  upon  each  of  these  divisions 
along  the  Atlantic  sea-board  of  North  America. 

Geology  is  that  brancli  of  knowledge  which  embodies  all 
ascertained  facts  in  regard  to  the  nature  and  internal  structure, 
both  physical  and  chemical,  of  the  solid  parts  of  our  globe. 
This  science  has  many  close  relations  with  practical  agriculture. 
It  especially  throws  much  light  on  the  nature  and  origin  of 
soils — on  the  causes  of  their  diversity — on  the  agricultural  capa- 
biUties,  absolute  and  comparative,  of  diflFerent  farming  districts 
and  countries — on  the  unlike  effects  produced  by  the  same 
manure  on  different  soils — on  the  kind  of  materials,  by  admix- 
ture with  which  they  may  be  permanently  improved — and  on 
the  sources  from  which  these  materials  may  be  derived. 

It  tells  beforehand,  also,  and  by  a  mere  inspection  of  the 
may,  what  is  the  general  character  of  the  land  in  this  or  that 
district  of  a  country — where  good  land  is  to  be  expected — where 
improvements  are  likely  to  be  effected — of  what  kind  of  im- 
provements this  or  that  district  will  be  susceptible — and  where 
the  intending  purchaser  may  hope  to  lay  out  his  money  to  the 
greatest  advantage. 

SECTION  I. OF  THE  CRUMBLING  OF  ROCKS  AND  THE  ORIGIN  OF  S0IL8. 

If  we  dig  down  through  the  soil  and  subsoil  to  a  sufficient 
depth,  we  always  come  sooner  or  later  to  the  solid  rock.     In 
many  places  the  rock  actually  reaches  the  surface,  or  rises  in 
4* 


82  GENERAL  COMPOSITION   OF   R0CE9. 

clifiFs,  hills,  or  ridges,  far  above  it.  The  surface  (or  crust)  of 
our  globe,  therefore,  consists  everywhere  of  a  more  or  less  solid 
mass  of  rock,  overlaid  by  a  covering,  generally  thin,  of  loose 
materials.  The  upper  or  outer  part  of  these  loose  materials 
forms  the  soil. 

The  geologist  has  travelled  over  great  part  of  the  earth's 
surface,  has  examined  the  nature  of  the  rocks  which  everywhere 
repose  beneath  the  soil,  and  has  found  them  to  be  very  unlike  in 
appearance,  in  hardness,  and  in  composition — ^in  different  coun- 
tries and  districts.  In  some  places  he  has  met  with  a  sandstone, 
in  other  places  a  limestone,  in  others  a  slate  or  hardened  rock 
of  clay.  But  a  careful  comparison  of  all  the  kinds  of  rock  he 
has  observed  has  led  him  to  the  general  conclusion  tJiat  they  are 
all  either  sandstones,  limestones,  or  days  of  different  degrees  of 
hardness,  or  a  mixture  in  different  p^vportions  of  two  or  more  of 
these  kinds  of  matter. 

When  the  loose  covering  of  earth  is  removed  from  the  sur- 
face of  any  of  these  rocks,  and  this  surface  is  left  exposed,  sum- 
mer and  winter,  to  the  action  of  the  winds  and  rains  and  frosts, 
it  may  be  seen  gradually  to  crumble  away.  Such  is  the  case 
even  with  many  of  those  which,  on  account  of  their  greater 
hardness,  are  employed  as  building-stones,  and  which,  in  the 
walls  of  houses,  are  kept  generally  dry  ;  how  much  more  with 
such  as  are  less  hard,  or  lie  beneath  a  covering  of  moist  earth, 
and  are  continually  exposed  to  the  action  of  water.  The  natural 
crumbling  of  a  naked  rock  thus  gradually  covers  it  with  loose 
materials,  in  which  seeds  fix  themselves  and  vegetate,  and  which 
eventually  form  a  soil.  The  soil  thus  produced  partakes  neces- 
sarily of  the  chemical  character  and  composition  of  the  rock  on 
which  it  rests,  and  to  the  crumbling  of  which  it  owes  its  origin. 
If  the  rock  be  a  sandstone,  the  soil  is  sandy — ^if  a  claystone,  it 
is  a  more  or  less  stiff  clay — if  a  limestone,  it  is  more  or  less 
calcareous — and  if  the  rock  consist  of  any  peculiar  mixture  of 
those  three  substances,  a  similar  mixture  is  observed  in  the 
earthy  matter  into  which  it  has  crumbled. 


KELATIONS   OF    SOILS   TO    ROCKS.  83 

Led  by  this  observation,  the  geologist,  after  comparing  the 
rocks  of  different  countries  with  one  another  compared  next  the 
soils  of  various  districts  with  the  rocks  on  which  they  immedi- 
ately rest.  The  general  result  of  this  comparison  has  been,  that 
in  almost  every  country  the  soils,  as  a  whole,  have  a  resemblance 
to  the  rocks  beneath  them,  similar  to  that  which  the  loose  earth 
derived  from  the  crumbling  of  a  rock  before  our  eyes  bears  to 
the  rock  of  which  it  lately  formed  a  part.  The  conclusion, 
therefore,  is  irresistible,  that  soils,  generally  speaking  have  been 
formed  by  the  crumbling  or  decay  of  the  solid  rocks — that  there 
was  a  time  when  these  rocks  were  naked  and  without  any  cover- 
ing of  loose  materials — and  that  the  accumulation  of  soil  has 
been  the  slow  result  of  the  natural  degradation  or  wearing 
away  of  the  solid  crust  of  the  globe. 

SECTION   II. CAUSE   OF  THE   DIVERSrTY   OF   THE   SOILS. 

The  cause  of  the  diversity  of  soils  iu  different  districts,  there- 
fore, is  no  longer  obscure.  If  the  subjacent  rocks  in  two  local- 
ities differ,  the  soils  met  with  there  are  likely  to  differ  also,  and 
in  an  equal  degree. 

But  why,  it  may  be  asked,  do  we  find  the  soil  in  some  coun- 
tries uniform  in  mineral*  character  and  general  fertility  over 
hundreds  or  thousands  of  square  miles,  while  in  others  it  varies 
from  field  to  field — the  same  farm  often  presenting  many  well- 
marked  differences  both  in  mineral  character  and  in  agricultural 
value  ?  A  chief  cause  of  this  is  to  be  found  in  the  mode  in 
which  the  different  rocks  are  observed  to  lie — upon  or  by  the 
side  of  each  other,  f 

1.  Geologists  distinguish  rocks  into  two  classes,  the  stratified 
and  the  wnstratified.  The  former  are  found  lying  over  each 
other  in  separate  beds  or  strata,  like  the  leaves  of  a  book  when 

*  That  is,  containing  the  same  general  proportions  of  sand,  clay,  lime,  4a, 
or  colored  red  by  similar  quantities  of  oxide  of  iron. 

f  For  another  important  cause,  see  Section  II.  of  Chapter  VIII. 


84 


STRATIFIED   AND    UNSTRATIFIED   ROCKS. 


laid  on  its  side,  or  like  the  layers  of  stones  in  the  wall  of  a 
building.  The  latter — the  unstratified  rocks — form  hills,  moun- 
tains, or  sometimes  ridges  of  mountains,  consisting  of  one  more 
or  less  solid  mass  of  the  same  material,  in  which  no  layers  or 
strata  are  usually  anywhere  or  distinctly  perceptible.  Thus,  in 
the  following  diagram,  (No.  1,)  A  and  B  represent  unstratified 
masses,  in  connection  with  a  series  of  stratified  deposits,  12  3, 
lying  over  each  other  in  a  horizontal  position.  On  A  one  kind 
of  soil  will  be  formed,  on  C  another,  on  B  a  third,  and  on  D  a 
fourth — the  rocks  being  all  different  from  each  other. 

No.  1. 

J3_ 


If  from  A  to  D  be  a  wide  valley  of  many  miles  in  extent,  the 
nudulating  plain  at  the  bottom  of  the  valley,  resting  in  great 
part  on  the  same  rock,  (2,)  will  be  covered  by  a  similar  soil. 
On  B  the  soil  will  be  different  for  a  short  space  ;  and  again  it 
will  differ  at  the  bottom  of  the  valley  C,  and  on  the  first  ascent 
to  A,  at  both  of  which  places  the  rock  (3)  rises  to  the  surface. 
In  this  case  the  stratified  rocks  lie  horizontally  ;  and  it  is  the 
undulating  nature  of  the  country  which,  bringing  different  kindp 
of  rock  to  the  surface,  causes  a  necessary  diversity  of  soil. 

2.  But  the  degree  of  inclination  which  the  beds  possess  is  a 
more  frequent  cause  of  variation  in  the  characters  of  the  soil 
in  the  same  district,  and  even  at  very  short  distances.  This 
is  shown  in  the  annexed  diagram,  (No.  2,)  where  ABODE 
represent  the  mode  in  which  the  stratified  rocks  of  a  district 
of  country  not  unfrequently  occur  in  connection  with  each 
other. 

No.  2. 


Proceeding  from  E  in  the  plain,  the  soil  would  change  when 


ORDER   OF   SUCCESSION   CONSTANT.  85 

we  came  upon  the  rock  D,  but  would  continue  pretty  uniform 
in  quality  till  we  reached  the  layer  C.  Each  of  these  layers 
may  stretch  over  a  comparatively  level  tract  of  perhaps  hun- 
dreds of  miles  in  extent.  Again,  on  climbing  the  hill-side, 
another  soil  would  present  itself,  which  would  not  change  till 
we  arrived  at  B.  Then,  however,  we  begin  to  walk  over  the 
edges  of  a  series  of  beds,  and  the  soil  may  vary  with  every 
new  stratum  or  bed  we  pass  over,  till  we  gain  the  ascent  to  A, 
where  the  beds  are  much  thinner,  and  where,  therefore,  still 
more  frequent  variations  may  present  themselves. 

Everywhere  over  the  British  islands  valleys  are  hollowed 
out,  as  in  the  former  of  these  diagrams,  (No.  1,)  by  which  the 
different  rocks  beneath  are  in  different  places  exposed  and  dif  ■ 
ferences  of  soil  produced  ;  or  the  beds  are  more  or  less  inclined, 
as  in  the  latter  diagram,  (No.  2,)  causing  still  more  frequent 
variations  of  the  land  to  appear.  By  a  reference  to  these  facts, 
therefore,  many  of  the  greater  diversities  which  the  soils  of  the 
country  present  may  be  satisfactorily  accounted  for. 

SECTION   III. OF    THE    CONSTANCY    IN     MINERAL    CHARACTER,     AND 

ORDER   OF     SUCCESSION,     WHICH    EXISTS     AMONG   THE    STRATIFIED 
ROCKS. 

Another  fact,  alike  important  to  agriculture  and  to  geology, 
is  the  natural  order  or  mode  of  arrangement  in  which  the  stra- 
tified rocks  are  observed  to  occur  in  the  crust  of  the  globe. 
Thus,  if  1  2  3  in  diagram  No.  1  represent  three  different  kinds 
of  rock — a  limestone,  for  example,  a  sandstone,  and  a  hard  clay 
rock  (a  shale  or  slate)  lying  over  each  other  in  the  order  here 
represented — then,  in  whatever  part  of  the  country,  nay,  in 
whatever  part  of  the  world  these  same  rocks  are  met  with, 
they  will  always  be  found  in  the  same  position.  The  bed  2  or 
3  will  never  he  observed  to  lie  over  the  bed  1. 

This  fact  is  important  to  geology,  because  it  enables  this 
science  to  arrange  all  the  stratified  rocks  in  a  certain  invariable 


86  DEDUCTIONS   FROM  THIS. 

order — which  order  indicates  their  relative  age  or  antiquity — 
since  that  rock  which  is  lowest,  like  the  lowest  layer  of  stones 
in  the  wall  of  a  building,  must  generally  have  been  the  first 
deposited,  or  must  be  the  oldest.  It  also  enables  the  geologist 
on  observing  the  kind  of  rock  which  forms  the  surface  in  any 
country,  to  predict,  at  once  whether  certain  other  rocks  are 
likely  to  be  met  with  in  that  country  or  not.  Thus  at  C, 
(diagram  No.  1,)  where  the  rock  3  comes  to  the  surface,  he 
knows  it  would  be  in  vain,  either  by  sinking  or  otherwise,  to 
seek  for  the  rock  1,  the  natural  place  of  which  is  far  above  it  ; 
while,  at  D,  he  knows  that  by  sinking  he  is  likely  to  find  either 
2  or  3,  if  it  be  worth  his  while  to  seek  for  them. 

To  the  agriculturist  this  fact  is  important,  among  other 
reasons, — 

1.  Because  it  enables  him  to  predict  whether  certain  kinds 
of  rock,  which  may  be  used  with  advantage  in  improving  his 
soil,  are  likely  to  be  met  with  within  a  reasonable  distance  or 
at  an  accessible  depth.  Thus,  if  the  bed  D  (diagram  No.  2) 
be  a  limestone,  the  instructed  farmer  at  E  knows  that  it  is  not 
to  be  found  by  sinking  into  his  own  land,  and  therefore  brings 
it  from  D  ;  while  to  the  farmer  upon  C  it  may  be  less  expen- 
sive to  dig  down  to  the  bed  D  in  one  of  his  own  fields,  than  to 
cart  it  from  a  distant  spot,  where  it  occurs  on  the  surface. 
Or,  if  the  farmer  requires  clay,  or  marl,  or  sand,  to  ameliorate 
his  soil,  this  knowledge  of  the  constant  relative  position  of  beds 
enables  him  to  say  where  these  materials  are  to  be  got,  or 
where  they  are  to  be  looked  for,  and  whether  the  advantage  to 
be  derived  is  likely  to  repay  thje  cost  of  procuring  them. 

2.  It  is  observed  that,  when  the  soil  on  the  surface  of  each 
of  a  series  of  rocks,  such  as  C  or  D  or  E,  (diagram  No.  2,)  is 
uniformly  bad,  it  is  almost  uniformly  of  better  quality  at  the 
point  where  the  two  rocks  meet.  Thus  C  may  be  dry,  sandy,  and 
barren  ;  D  may  be  a  cold  unproductive  clay  ;  and  E  a  more 
or  less  unfruitful  limestone  soil  ;  yet  at  either  extremity  of  the 
tract  D,  where  the  soil  is  made  up  of  an  admixture  of  the 


PRACTICAL  VALUE   OP   GEOLOGICAL   KNOWLEDGE.  8t 

decayed  portions  of  the  two  adjacent  rocks,  the  land  may  be 
of  average  fertility — the  sand  of  C  may  adapt  the  adjacent 
clay  to  the  growth  of  turnips,  while  the  lime  of  E  may  cause  it 
to  yield  large  returns  of  wheat.*  Thus,  to  the  tenant  in  look- 
ing out  for  a  farm,  or  to  the  capitalist  in  seeking  an  eligible 
investment,  a  knowledge  of  the  mutual  relations  of  geology 
and  agriculture  will  often  prove  of  the  greatest  assistance. 
But  how  little  is  such  really  useful  knowledge  difiiised  among 
either  class  of  men — how  little  have  either  tenants  or  proprie- 
tors been  hitherto  guided  by  it  in  their  choice  of  the  local- 
ities in  which  they  desire  to  live  I 

3.  The  further  fact  that  the  several  stratified  rocks  are  re- 
markably constant  in  their  general  mineral  character,  renders 
this  knowledge  of  the  order  of  relative  superposition  still  more 
valuable  to  the  agriculturist.  Thousands  of  different  beds 
are  known  to  geologists  to  occur  on  various  parts  of  the  earth's 
surface — each  occupying  its  own  unvarying  place  in  the  series. 
Most  of  these  beds  also,  when  they  crumble  or  are  worn  down, 
produce  soils  possessed  of  some  peculiarity  by  which  their 
general  agricultural  capabilities  are  more  or  less  affected, — and 
these  peculiarities  may  generally  be  observed  in  soils  formed 
from  rocks  of  the  same  age — that  is,  occupying  the  same  place 
in  the  series — in  whatever  part  of  the  world  we  find  them. 
Hence,  if  the  agricultural  geologist  be  informed  that  his  friend 
has  bought,  or  is  in  treaty  for  a  farm  or  an  estate,  and  that  it 
is  situated  upon  such  and  such  a  rock,  or  geological  formation, 
or  is  in  the  immediate  neighborhood  of  such  another, — he  can 
immediately  give  a  very  probable  opinion  in  regard  to  the 
agricultural  value  of  the  soil,  whether  the  property  be  in  Eng- 
land, Ajistralia,  or  in  New  Zealand.  If  he  knows  the  nature 
of  the  climate  also,  he  will  be  able  to  estimate  with  tolerable 
correctness  how  far  the  soil  is  likely  to  repay  the  labors  of 
the  practical  farmer — nay,  even  whether  it  is  likely  to  suit 
better  for  arable  land  or  for  pasture  ;  and  if  for  arable,  what 

*  See  p.  84. 


88  AGRICULTURAL  VALUE  OF  GEOLOGY, 

species  of  grain  and  root  crops  may  be  expected  to  produce 
most  abundantly. 

These  facts  are  so  very  curious,  and  illustrate  so  beautifully 
the  value  of  geological  knowledge — if  not  to  A  and  B,  the  holders 
and  proprietors  of  this  and  that  small  farm,  yet  to  enlightened 
agriculturists,  to  scientific  agriculture  in  general — that  I  shall 
explain  this  part  of  the  subject  more  fully  in  a  separate  section. 
To  those  who  are  now  embarking  in  such  numbers  in  quest  of 
new  homes  in  our  numerous  colonies — who  hope  to  find,  if  not  a 
more  willing,  at  least  a  more  attainable  soil  in  new  countries — 
no  kind  of  agricultural  knowledge  can  at  the  outset, — I  may 
say,  even  through  life — be  so  valuable  as  that  to  which  the  rudi- 
ments of  geology  will  lead  them.  Those  who  prepare  themselves 
the  best  for  becoming  farmers  or  proprietors  in  Canada,  in 
New  Zealand,  or  in  wide  Australia,  leave  their  native  land  in 
general  without  a  particle  of  that  preliminary  practical  know- 
ledge which  would  qualify  them  to  say,  when  they  reach  the 
land  of  their  adoption,  "on  this  spot  rather  than  on  that 
— ^in  this  district,  rather  than  that, — will  I  purchase  my 
allotment,  because  though  both  appear  equally  inviting,  yet 
I  know,  from  the  geological  structure  of  the  country,  that 
here  I  shall  have  the  more  permanently  productive  soil ; 
here  I  am  more  within  reach  of  the  means  of  agricultural  im- 
provement; here,  in  addition  to  the  riches  of  the  surface,  my 
descendants  may  hope  to  derive  the  means  of  wealth  from  mine- 
ral riches  beneath."  And  this  oversight  has  arisen  chiefly  from 
the  value  of  such  knowledge  not  being  understood — often  from 
the  very  nature  of  it  being  unknown,  even  to  otherwise  well- 
instructed  practical  men.  It  is  not  to  men  well  skilled  merely 
In  the  details  of  local  farming,  and  who  are  therefore  deservedly 
considered  as  authorities,  and  good  teachers  in  regard  to  local 
or  district  practice,  that  we  are  to  look  for  an  exposition,  often 
not  even  for  a  correct  appreciation  of  those  general  principles 
on  which  a  universal  system  of  agriculture  must  be  based — 
without  which,  indeed,  it  must  ever  remain  a  mere  collection  of 


SUBDIVISIONS   OP   STRATIFIED   ROCKS.  89 

empirical  rules,  to  be  studied  and  laboriously  mastered  in  every 
new  district  we  go  to — as  the  traveller  in  foreign  lands  must 
acquire  a  new  language  every  successive  frontier  he  passes. 
England,  the  mistress  of  so  many  wide  and  unpeopled  lands, 
over  which  the  dwellings  of  her  adventurous  sons  are  hereafter 
to  be  scattered,  on  which  their  toil  is  to  be  expended,  and  the 
glory  of  their  motherland  by  their  exertions  to  be  perpetuated — 
England  should  especially  encourage  all  such  learning,  and  the 
sons  of  English  farmers  should  willingly  avail  themselves  of 
every  opportunity  of  acquiring  it. 

SECTION   IV. OF    THE     SUBDIVISIONS    OF    THE    STRATIFIED    ROCKS, 

AND    OF   OBSERVED    DIFFERENCES    AMONG    THE    SOILS   THAT   REST 
UPON   THEM. 

The  thousands  of  beds  or  strata  of  which  I  have  spoken  as 
lying  one  over  the  other  in  the  crust  of  the  globe,  have- — partly 
for  convenience,  and  partly  in  consequence  of  certain  remarkably 
distinctive  characters  observed  among  them — been  separated  by 
geologists  into  three  great  divisions.  The  'primary  are  the 
lowest  and  the  oldest ;  the  secondary  lie  over  these ;  and  the  terti- 
ary are  the  uppermost,  and  have  been  most  recently  formed.  The 
sands,  gravels,  clays,  and  alluvial  deposits,  which  in  many  places 
overlie  the  soUd  rocks  and  the  beds  of  soft  limestone,  in  many 
places  formed  by  calcareous  springs,  are  often  spoken  of  as  post- 
tertiary. 

In  some  countries,  on  the  surface  of  which  these  several 
divisions  of  the  strata  are  seen  to  succeed  each  other  very  closely, 
the  character  of  the  surface  soil  and  its  agricultural  capability 
are  also  seen  to  vary  as  we  pass  from  the  rocks  of  the  one  epoch 
to  those  of  the  other.  This  is  the  case,  for  example,  in  the  more 
southernly  of  the  United  States  of  America  which  lie  along  the 
Atlantic  border.  As  we  walk  inland  from  the  sea-shore,  we 
pass  over  low  and  swampy,  but  rich  muddy  flats,  which  yield 
large  returns  of  sea-island  cotton  and  rice.    As  we  proceed,  the 


Mi  DIFFERENT  ROCKS   OP  THE 

ground  gradually  rises  above  the  sea-level — ^becomes  firmer  and 
drier — and  instead  of  the  swamp  willow  and  cypress,  bears  the 
hickory  and  the  oak.  Tobacco  and  sugar  are  the  marketable 
crops  on  this  drier  land,  and  Indian  corn  the  staple  food  of  the 
colored  population.  After  twenty  miles  or  so,  the  edge  of  this 
drier  alluvial  plain  is  reached,  and  we  ascend  a  low  escarpment 
or  terrace  of  yellow  sand.  Here  we  find  ourselves  amid  thin 
forests  of  unmixed  natural  pine,  growing  upon  a  poor  sandy 
soil;  and  till  we  cross  this  belt  and  reach  a  second  terrace,  few 
corn-fields,  or  attempts  at  clearing  for  the  purposes  of  cultiva- 
tion meet  the  eye.  The  new  terrace  presents  the  remarkable 
contrast  of  an  open  prairie,  void  of  trees,  covered  with  a  thin 
soil  waving  with  grass,  and  resting,  like  our  English  downs,  on 
chalk  rocks  beneath.  This  tract  is  dry  and  deficient  in  water; 
but  the  thin  soil,  when  turned  over,  yields  crops  of  corn,  and 
bears,  among  others,  a  variety  of  hard  wheat,  known  in  the 
market  by  the  name  of  Georgian  wheat.  Still  farther  on  this 
prairie  is  passed,  and  we  ascend  hilly  slopes,  upon  which  clays 
and  loams  of  various  qualities  and  capabilities  occur  at  intervals 
intermingled,  and  broad-leaved  trees  of  various  kinds  ornament 
the  landscape.  It  is  a  country  fitted  for  general  husbandry, 
propitious  to  skill  and  industry,  and,  by  its  climate,  adapted  to 
the  constitution  of  settlers  of  European  blood. 

These  changes  in  agricultural  character  and  capability  are 
coincident  with  changes  in  the  geological  age  of  the  beds  wliich 
form  its  surface.  This  I  have  shown  in  the  following  section  of 
the  coast-line  in  question,  from  the  sea  to  the  mountains.  The 
letterpress  below  the  section  indicates  the  geological  formations; 
that  placed  above  it  indicates,  first,  the  natural  vegetation,  and 
theu  the  kind  of  husbandry  and  of  labor  which  are  best  adapted 
to  each. 


AMERICAN  ATLANTIC   BORDER. 


91 


No.  3.  Broad-leaved  forests 

Oak  

Swamp     and  General  husbandry 

willow,  hickory.  

Dry  chalk  downs.     "White  labor. 

Rice        Sugar      Pine  forests.     Treeless  prairies. 

and  and      Sandy  barrens.  

cotton,    tobacco.         Georgian  wheat. 

Little  cultivation. 

Colored  labor. 


Sea.    Post-tertiary,    Tertiary  sands.    Secondary  Primary  metamorphic* 
and  alluvial.  chalk  marks.        rocks  and  granite. 

In  this  section  the  reader  will  observe  a  close  general  relation 
between  the  changes  in  geological  and  agricultural  character 
which  appear  on  the  several  successive  terraces  or  flats  of  land 
which  intervene  between  the  shores  of  the  Atlantic  and  the  slopes 
of  the  Alleghany  Mountains.  Where  the  most  recent  or  alluvial 
loams  and  rich  clays  end,  there  the  tobacco,  Indian  corn,  and  even 
wheat  culture,  for  the  time,  end  also.  The  tertiary  sands  be- 
long to  a  more  ancient  epoch,  and  to  them  are  limited,  by  a 
strictly  defined  boundary  on  each  side,  the  dark  pine  forests 
which  are  so  striking  a  feature  of  the  country.  On  the  still 
older  chalk,  again,  the  treeless  prairie  and  flinty  wheat  country 
is  as  distinctly  limited  by  the  formations  on  either  hand;  and 
beyond  this,  again,  the  changed  forests  and  cultivation  of  tho 
higher  country  are  determined  by  the  change  in  nature  and  in 
age  which  the  rocks  of  this  region  exhibit. 

*  The  word  metamorphic  here  used  means  changed  or  altered — as  clay, 
for  example,  is  changed  when  it  is  baked  into  tiles  or  bricks. 


CHAPTER  YII. 

SabdiriBioDS  of  the  tertiary,  secondary,  and  primary  groups  of  rocks. — 
Agricultiiral  relations  of  the  crag  and  London  clay. — Fossil  phosphates 
of  the  crag;  quantity  and  value  of  these. — Soils  of  the  London  and 
plastic  clays. — Of  the  chalk  and  green-sand. — Ware  malt. — Clays  of 
the  Weald  and  Lias. — Rich  soils  of  the  new  red  saud.stone. — Contrast 
between  those  of  the  millstone  grit  and  mountain  hmestone. — Soils  of  the 
Silurian,  Cambrian,  and  Mica  slate  rocks.  General  conclusions  as  to  the 
relations  of  geology  to  agriculture. 

But  the  several  great  groups  of  strata,  of  which  we  have 
spoken  under  the  names  of  primary,  secondary,  &c.,  are  them- 
selves broken  up  or  subdivided  by  geologists  into  a  variety  of 
subdivisions  called  systems  and  formations,  each  of  which  pos- 
sesses its  peculiar  mineral  characters  and  special  agricultural 
relations.  These,  in  so  far  as  relates  to  the  geology  of  our  own 
country,  it  will  be  proper  briefly  to  indicate. 

SECTION   I. THE   TERTIARY   STRATA. 

The  tertiary  strata,  as  they  occur  in  England,  consist  chiefly 
of  the  crag,  which  lies  above,  and  the  London  and  plastic  clays, 
which  follow  each  other  underneath. 

1.  The  Crag  consists  of  a  mass  of  rolled  pebbles  mixed  with 
marine  shells  and  corals,  and  resting  upon  beds  of  sand  and 
marl.  It  is  in  places  as  much  as  50  feet  in  thickness,  though 
generally  of  less  depth,  and  forms  a  strip  of  flat  land,  a  few 
miles  in  width,  along  the  eastern  shores  of  Norfolk  and  Suffolk. 
The  soil  is  generally  fertile,  but  varies  in  value  from  5s,  to  258. 
an  acre  of  rent. 

This  crag  is  chiefly  interesting  to  the  agriculturist  from  its 


NODULES  OF   PHOSPHATE   OF  LIME.  93 

containing  hard,  rounded,  flinty  nodules — often  spoken  of  as 
eoprolites — ^in  which  as  much  as  50  per  cent  of  phosphate  of  lime 
^^tone-earth)  is  frequently  found.  These  nodules  are  scattered 
through  the  body  of  the  marls,  and  through  the  subsoils  of  the 
fields  far  inland,  and  are  collected  for  sale  to  the  manufacturers 
of  super-phosphate  of  lime  and  other  artificial  manures.  Some 
parties  are  said  to  have  dug  up  as  much  as  60  or  10  tons  a-week.* 

2.  The  London  and  plastic  clays,  from  500  to  900  feet  thick, 
consist  of  stiff,  almost  impervious,  dark-colored  clays — the  soils 
formed  from  which  are  still  chiefly  in  pasture.  The  lower  beds — 
the  plastic  clay — are  mixed  with  sand,  and  produce  an  arable 
Boil ;  but  extensive  heaths  and  wastes  rest  upon  them  in  Berk- 
shire, Hampshire,  and  Dorset.  The  crops  of  corn  and  roots 
yielded  by  the  stiff  clay  soils  of  these  strata  have  hitherto,  in 
many  districts,  been  found  insufiBcient  to  pay  the  cost  of  raising 
them.  The  drain  and  the  subsoil  plough,  with  lime  or  chalk- 
in  which  these  clays  are  very  deficient,  and  for  the  addition  oi 
which  they  are  very  grateful — would  render  ihem  more  produc- 
tive and  more  profitable  to  the  farmer. 

SECTION   II. THE    SECONDARY   STRATA, 

3.  The  Chalk,  about  600  feet  in  thickness,  lies  below  the  Lon- 
don and  plastic  clays  above  described.  It  consists — as  shown 
in  the  section  No.  4 — in  the  upper  part,  of  a  purer  chalk  with 


*  The  cost  of  digging  up,  screening,  cleaning,  &c.,  of  these  nodules,  is 
about  5s.  a  ton,  and  they  are  delivered  on  board  the  vessel  at  30s.  to  45s. 
The  quantity  of  the  fossils  which  is  scattered  over  this  part  of  tlie  county, 
and  the  treasure  they  are  now  proving  to  the  owners  of  the  land,  may  be 
judged  of  from  two  facts  stated  by  Mr.  Herapath,  (Jour.  Royal  Agric.  Soc, 
xii.  p.  93,)  "that  £60,  £70,  and  £80,  have  been  repeatedly  given  for  leave 
to  dig  over  a  two-acre  field;"  and  "that  the  land  itself  is  actually  improved 
by  the  course  of  treatment  to  which  it  is  subjected  when  excavating  for  the 
fnwriin, 


94 


THE  CHALK  AND  GREEN-SAND. 


Suffolk. 


No.  4. 

Mouth  of  the  Thames. 


Kent 


1.  London  clay. 

2.  Plastic  clay. 


3.  Upper  chalk,  with  flints. 

4.  Under  chalk,  without  flints. 


layers  of  flint,  (3)  ;  in  the  lower,  of  a  marly  chalk  withoal 
flints,  (4.)  The  soil  of  the  upper  chalk  is  chiefly  in  sheep- 
walks  ;  that  of  the  lower  chalk  is  very  productive  of  corn.  In 
some  localities,  (Croydon,)  the  arable  soils  of  the  upper  chalk 
have  lately  been  rendered  much  more  productive  in  corn  and 
beans  by  deep  ploughing,  and  thus  mixing  with  the  upper  soil  as 
much  as  6  or  8  inches  of  the  inferior  chalk.  Excellent  crops  of 
carrots  also  have  been  obtained  by  deep-forking  such  land. 

The  general  and  comparative  agricultural  value  of  the  soils 
upon  the  chalk  may,  to  a  certant  extent,  be  judged  of  by  the 
fact,  that,  in  the  lowest-rented  counties  in  England,  chalk  is  the 
prevailing  rock. 

4.  The  Green-sand,  500  feet  thick,  consists  of  150  feet  of 
clay,  with  about  100  feet  of  a  greenish,  more  or  less  indurated, 
sand  above,  and  250  feet  of  sand  or  sandstone  below  it.  The 
upper  sand  forms  a  very  productive  arable  soil ;  but  the  clay 
forms  impervious  wet  and  cold  lands,  chiefly  in  pasture.  The 
lower  sand  is  generally  unproductive. 

In  the  green-sand,  both  upper  and  lower,  but  especially  in  the 
upper,  beds  of  marl  occur,  in  which  are  found  layers  of  so-called 
coprolites  and  other  organic  remains,  rich  in  phosphate  of  lime. 
To  the  presence  of  these  beds  is  ascribed  the  fertility  of  the 
soil  of  the  upper  green-sand,  which  in  some  localities  is  very 
remarkable,  and,  as  at  Farnham  in  Surrey,  is  found  to  be  espe- 
cially favorable  to  the  growth  of  hops.  The  organic  remains  are 
in  some  places  so  abundant,  that,  as  in  the  crag,  they  are  scaghfc 


FERTILITY   OF   MKED   SOILS.  9j 

Jot  and  dug  up,  as  a  natural  source  of  the  phosphate  of  lime, 
usually  supplied  to  the  soil  directly  in  the  form  of  bones. 

It  is  an  important  agricultural  remark,  that  where  the  plastit 
clay  comes  in  contact  with  the  top  of  the  chalk,  an  improved 
soil  is  produced ;  and  that  where  the  chalk  and  the  green-sand 
mix,  extremely  fertile  patches  of  country  present  themselves. 

The  following  imaginary  section  shows  the  relative  positions 
of  these  two  fertile  strips  of  country,  above  and  below  the  chalk. 

At  the  contact  with  the  plastic  clay  it  is  particularly  adapted 
for  the  growth  of  barley,  which,  for  quality  and  malting  proper- 
ties, is  not  excelled  by  any  in  the  kingdom.  In  Essex,  barley 
grown  on  this  soil  is  principally  sold  to  maltsters  at  Stortford, 
&c, ;  and  when  malted,  is  sold  again  in  London  under  the  name 
of  "Ware  malt.  This  name  is  derived  from  Ware  in  Hertford- 
shire, a  market  town  standing  on  a  similar  soil. 

No.  5, 
Wheat  and  hop  land.  Barley  soila. 


The  soils  at  the  contact  of  the  chalk  and  upper  green-sand 
are  celebrated  for  their  crops  of  wheat,  in  producing  which  the 
phosphates  in  the  marls  of  the  upper  green-sand  are  supposed  to 
have  some  influence. 

5.  The  Wealden  formation,  which  succeeds  the  green-sand,  is 
nearly  1000  feet  thick,  and  consists  of  400  feet  of  sand,  covered 
by  300  of  clay,  resting  upon  250  of  marls  and  limestones. 
The  clay  forms  the  poor,  wet,  but  improvable  pastures  of  Sus- 
sex and  Kent.  These  clays,  in  many  places,  harden  like  a 
brick  when  dried  in  the  air  ;  and  clods  which  have  lain  long  in 
the  sun,  ring,  when  struck,  like  a  piece  of  pottery.  By  dram- 
mg  alone,  their  produce  has  been  raised  from  16  to  40  bushels 
of  wheat  an  acre.  On  the  sands  below  the  clay  rest  heaths 
and  brushwood  ;  but  where  the  marls  and  limestones  oosoa  to 


96  THE  WEALDEN  AND  OXFORD  CLAYS. 

the  surface,  the  land  is  of  better  quality,  and  is  susceptible  of 
profitable  arable  culture. 

6,  In  the  Upfer  oolite,  of  600  feet  in  thickness,  we  have  a 
bed  of  clay  (Kimmeridge  clay)  500  feet  thick,  covered  by  100 
feet  of  sandy  limestones.  The  clay  lands  of  this  formation  are 
difficult  and  expensive  to  work,  and  are  therefore  chiefly  in  old 
pasture.  The  sandy  limestone  soils  above  the  clay  are  also 
poor  ;  but  where  they  rest  immediately  upon,  and  are  inter- 
mixed with,  the  clay,  excellent  arable  land  is  produced. 

1.  The  Middle  oolite,  of  500  feet,  consists  also  of  a  clay, 
(Oxford  clay,)  dark  blue,  adhesive,  often  rich  in  lime,  and 
nearly  400  feet  thick,  covered  by  100  feet  of  limestones  and 
sandstones.  These  latter  produce  good  arable  land  where  the 
lime  happens  to  abound,  but  the  clays,  especially  while  un- 
valued, form  close  heavy  compact  soils,  most  difficult  and  ex- 
pensive to  work.  In  wet  weather  they  are  often  adhesive  like 
oird-lime,  and  in  dry  summers  become  hard  like  stone,  so  as  to 
require  a  pick-axe  to  break  them.  They  have  therefore  hitherto 
been  very  partially  brought  into  arable  culture.  The  extensive 
pasture-lands  of  Bedford,  Huntingdon,  Northampton,  liincoln, 
Wilts,  Oxford,  an^l  Gloucester,  rest  chiefly  upon  this  clay  ;  as 
do  also  the  fenny  tracts  of  Lincoln  and  Cambridge.  The  use 
of  burned  clay  upon  the  arable  land  has,  in  some  parts  of  this 
clay  district,  been  of  much  advantage. 

8.  The  Lower  or  Bath  oolite,  of  500  feet  in  thickness,  con- 
sists of  many  beds  of  limestone  and  sandstone,  with  about  200 
feet  of  clay  in  the  centre  of  the  formation.  The  soils  are  very 
various  in  quality,  according  as  the  sandstone  or  limestone  pre- 
dominates in  each  locality.  The  clays  are  chiefly  in  pasture  : 
the  rest  is  more  or  less  productive,  easily  worked,  arable  land. 
In  Gloucester,  Northampton,  Oxford,  the  east  of  Leicester, 
and  in  Yorkshire,  this  formation  is  found  to  lie  immediately 
beneath  the  surface,  and  a  little  patch  of  it  occurs  also  on  the 
south-eastern  coast  of  Sutherland. 

9.  The  Lias  is  an  immense  deposit  of  blue  clay,  from  500  to 


THE    COAL   MEASTTRKS.  97 

1000  feet  in  thickness,  which  produces  cold,  blue,  unproductive 
clay  soils.  It  forms  a  long  stripe  of  land,  of  varying  breadth, 
which  extends,  in  a  south-western  direction,  from  the  mouth  of 
the  Tees,  in  Yorkshire,  to  Lyme  Regis,  in  Dorset.  It  is  chiefly 
in  old,  and  often  very  valuable  pasture.  An  efficient  system  of 
drainage  will  by-and-by  convert  much  of  this  clay  into  most 
productive  wheat  land. 

10.  The  Wew  red  sandstotie,  though  only  500  feet  in  thickness, 
forms  the  surface  of  nearly  the  whole  central  plain  of  Eng- 
land, and  stretches  northwards  through  Cheshire  to  Carlisle 
and  Dumfries.  It  consists  of  red  sandstones  and  red  marls, 
the  soils  produced  from  which  are  easily  and  cheaply  worked, 
and  form  some  of  the  richest  and  most  productive  arable  lands 
in  the  island.  This  is  in  some  degree  indicated  by  the  fact  that 
the  three  highest-rented  counties  in  England  rest  chiefly  upon 
this  rock.  In  whatever  part  of  the  world  the  red  soils  of  this 
formation  have  been  met  with,  they  have  been  found  to  possess 
in  general  the  same  valuable  agricultural  capabilities. 

11.  The  Magne.sian  limestone,  from  100  to  500  feet  in  thick- 
ness, is  covered  by  a  stripe  of  generally  poor  thin  soU,  extend- 
ing from  Durham  to  Nottingham,  capable  of  improvement  as 
arable  land  by  high  farming,  but  bearing  naturally  a  poor  pas- 
ture, intermingled  with  sometimes  magnificent  furze. 

12.  The  Coal  measures,  from  300  to  8000  feet  thick,  consist 
of  beds  of  grey  sandstone,  and  of  dark  blue  shale,  or  har- 
dened clay,  intermingled  (inter-stratified)  with  beds  of  coal. 
Where  the  sandstones  come  to  the  surface,  the  soil  is  thin,  poor, 
hungry,  sometimes  almost  worthless.  The  shales,  on  the  other 
hand,  produce  stiff,  wet,  almost  unmanageable  clays — ^not  un- 
workable, yet  expensive  to  v,'ork,  and  requiring  draining,  lime, 
skill,  capital,  and  a  zeal  for  improvement  to  be  applied  to  them, 
before  they  can  be  made  to  yield  the  remunerating  crops  of 
corn  they  are  capable  of  producing.  The  blaes  or  shales  of 
this  formation,  when  dug  out  of  cliffs  or  brought  from  coal- 
mines, may  be  laid  with  advantage  on  loose  sandy  soils,  and 

6 


96 


MILLSTONE   GBn. 


even,  it  is  said,  on  the  stiff  whitish  clays  almost  destitute  of 
vegetable  matter,  which,  as  in  Lanarkshire,  occasionally  occur 
on  the  surface  of  our  coal-fields. 

13.  To  the  Millstone  grit,  of  600  feet  or  upwards  in  thick- 
ness, the  same  remarks  apply.  It  lies  below  the  coal,  but  m 
often  only  a  repetition  of  the  sandstones  and  shales  of  the 
coal  measures,  and  forms  in  many  cases  soils  still  more  worth- 
less. Where  the  sandstones  prevail,  large  tracts  lie  naked,  or 
bear  a  thin  and  stunted  heath.  Where  the  shales  abound,  the 
naturally  difficult  soils  of  the  coal  shales  again  recur.  The 
rocks  of  this  formation  generally  approach  the  surface,  around 
the  outskirts  of  our  coal-fields. 

This  arises  from  the  circumstance  that  our  coal  measures 
often  lie  in  basin-shaped  deposits,  from  beneath  each  edge  of 
which,  the  millstone  grit  and  mountain  limestone  rocks  rise  up 
to  the  surface.  This  is  illustrated  by  the  annexed  section,  (No. 
6,)  across  a  part  of  Lancashire,  in  which  1  represents  the  coal 
measures  ;  2  the  coarse  sandstones,  &c.  of  the  millstone  grit ; 
3  a  thick  shale-bed,  which  often  overlies  the  thick  masses  of 
mountain  limestone  represented  by  4. 

No.  6. 
Pendle  hilL  Boulsworth  hilL 

1803.  1689. 


The  traveller  passes  off  the  poor,  often  cold  and  wet,  clay 
Boils  of  the  coal  measures,  on  to  the  equally  poor  lands  cf 
the  millstone  grit,  and  over  its  top,  as  at  Pendle  hill,  descends 
upon  the  sweet  herbage  and  rich  dairy  pastures  of  the  moun. 
tain  limestone  at  4. 

The  section  shows  also  how  in  this  country  the  millstone  grit 


OLD   RED   SANDSTONE    SOILS.  99 

often  rises  into  high  hills.  These  are  then  covered  with  poor 
heaths  and  worthless  moors,  while  limestone  hills  of  equal 
height  bear  green  herbage  to  the  very  top. 

14.  The  Mountain  limestone,  800  to  1000  feet  thick,  is  a  hard 
blue  limestone  rock,  separated  here  and  there  into  distinct  beds 
by  layers  of  sandstones,  of  sandy  slates,  or  of  bluish-black 
shales  like  those  or  the  coal  measures.  The  soil  upon  the 
limestone  is  generally  thin,  but  produces  a  naturally  sweet 
herjDage,  everywhere  superior  in  value  to  that  which  grows  on 
the  sandier  soils  of  the  millstone  grit.  When  the  limestone 
and  clay  (shale)  adjoin  each  other,  as  where  3  and  4  in  the 
section  meet,  arable  land  occurs,  which  is  naturally  productive 
of  oats,  and  where  the  climate  is  favourable,  may,  by  skilful 
treatment,  be  converted  into  good  wheat  land.  In  the  north 
of  England — in  Derbyshire,  for  example,  and  among  the  York- 
shire dales — a  considerable  tract  of  country  is  covered  by 
these  rocks  ;  but  in  Ireland  they  form  nearly  the  whole  of  the 
interior  of  the  island. 

15.  The  Old  red  sandstone  varies  in  thickness  from  500  to 
10,000  feet.  It  possesses  many  of  the  valuable  agricultural 
qualities  of  the  n^w  red,  (No.  10,)  consisting,  like  it,  of  red 
sandstones  and  red  marls,  which  crumble  down  into  rich  red 
soils.  Such  are  the  soils  of  Brecknock,  Hereford,  and  part  of 
Monmouth  ;  of  part  of  Berwick  and  Roxburgh  ;  of  Hadding- 
ton and  Lanark  ;  of  southern  Perth  ;  of  either  shore  of  the 
Moray  Firth  ;  and  of  part  of  Sutherland,  Caithness,  and  the 
Orkney  islands.  In  Ireland,  also,  these  rocks  abound  in  Tyrone, 
Fermanah,  and  Monahan  ;  in  Waterford,  in  Mayo,  and  in 
Tipperary.  In  all  these  places  the  soils  they  form  are  generally 
the  best  in  their  several  neighborhoods.  Here  and  there, 
however,  where  the  sandstones  are  harder,  more  silicious  and 
impervious  to  water,  tracts,  sometimes  extensive,  of  heath  and 
bog  occur  ;  while  in  others  the  rocks  have  crumbled  into  hun- 
gry sands,  which  swallow  up  the  manure,  and  are  expensive  tc 
maintain  in  arable  culture. 


100  THE   PRIMARY  STRATA. 


SECTION  III.   THE   PRIMARY   STRATA. 

The  primary  stratified  rocks,  which  lie  underneath  all  those 
already  described,  are  separable  into  three  natural  divisions  ; 
the  Silurian*  above,  which  contain  the  remains  of  animals  in 
a  fossil  state  ;  the  Cambrian^  below,  in  which  no  animal 
remains  have  yet  been  discovered  ;  and,  lowest  of  all,  the 
mica  slate  and  gneiss  rocks,  which  exhibit  marks  of  change  or 
alteration  by  the  agency  of  heat.  Hence  these  last  are  often 
spoken  of  as  metamorpkic,  or  changed  rocks. 

16.  The  Upper  Silurian  system  is  nearly  4000  feet  in  thick- 
ness, and  forms  the  soils  which  cover  the  lower  border  counties 
of  Wales.  It  consists  of  sandstones  and  shales,  with  occasional 
limestones  ;  but  the  soils  formed  from  these  beds  take  their 
character  from  the  general  abundance  of  the  clay.  They  are 
cold — usually  unmanageable  muddy  clays  ;  with  the  remarkably 
inferior  agricultural  value  of  which  the  traveller  is  immediately 
struck,  as  he  passes  westward  from  the  red  sandstones  of 
Hereford  to  the  Upper  Silurian  rocks  of  the  county  of  Radnor. 

It.  The  Loxoer  Silurian  rocks  are  many  thousand  feet  in 
thickness,  and  in  Wales  lie  to  the  west  and  north  of  the  Upper 
Silurian  rocks.  They  consist,  on  the  upper  part,  of  about 
25,000  feet  of  sandstone,  on  which,  when  the  surface  is  not 
naked,  barren  heaths  alone  rest. . 

Beneath  these  sandstones  lie  1200  feet  of  sandy  and  earthy 
limestones,  from  the  decay  of  which,  as  may  be  seen  on  the 
southern  edge  of  Caermarthen,  fertile  arable  lands  are  produced. 

The  high  land,  which  stretches  across  the  whole  of  southern 
Scotland,  from  St.  Abb's  head  to  Portpatrick,  including  the 
Lammermuir  hills,  so  far  as  they  have  yet  been  examined,  con- 
sists of  strata  belonging  to  the  upper  part  of  the  Lower  Silu- 
rian, and  the  lower  part  of  the  Upper  Silurian.    The  soils  in 

*  Or  older  Falaiozoic,  as  containing  evidences  of  most  ancient  life, 
f  Or  Azoic,  from  containing  no  traces  of  life. 


CAMBRIAN   SYSTEM,    MICA   SLATK,    AND   GNEISS.  101 

geiieral  are  of  inferior  quality,  the  slaty  rocks  crumbling  witli 
difficulty,  and  being  poor  in  lime.  Cold  and  infertile  farms 
cover  the  higher  grounds,  and  wide  heathy  moors  and  bogs. 

18.  The  Cambrian  system — meaning  by  this  term  unaltered 
rocks,  containing  no  fossils — is  at  present  a  subject  of  dispute 
among  geologists,  and  its  limits  even  in  our  own  island  are  not 
well  defined.  It  is  probably  many  thousand  feet  in  thickness — 
lies  beneath  the  Lower  Silurian — and  in  its  agricultural  re- 
lations has  much  resemblance  to  these  rocks.  It  consists  in 
great  part  of  slaty  rocks,  more  or  less  hard,  which  often  crum- 
ble very  slowly,  and  almost  always  produce  either  poor  and 
thin  soils — or  cold,  difficultly  manageable  clays,  expensive  to 
work,  and  requiring  high  farming  to  bring  them  into  profitable 
arable  cultivation.  In  Cornwall,  western  Wales,  the  mountains 
of  Cumberland  ;  in  the  mountains  of  Tipperary,  in  the  extreme 
south  of  Ireland,  on  its  east  coast,  and  far  inland  from  the  bay 
of  Dundalk,  such  slaty  rocks  occur,  though  the  limits  of  the 
two  formations  have  not  been  everywhere  defined.  Patches  of 
rich,  well-cultivated  land  occur  here  and  there  in  these  districts, 
with  much  also  that  is  improvable  ;  but  the  greater  part  is 
usurped  by  worthless  heaths  and  extensive  bogs.  On  the  dif- 
ficult soils  of  those  formations — thinly  peopled,  inhabited  by 
small  farmers  with  little  capital,  and  therefore  hitherto  neglected 
— ^much  improvement  is  now  here  and  there  appearing  ;  and 
the  introduction  of  the  drain  promises  to  make  much  corn 
grow,  where  little  food,  either  for  man  or  beast,  was  previously 
produced.  These  rocks  in  general  contain  little  lime,  and 
therefore,  after  the  drain,  the  addition  of  lime  is  usually  one  of 
the  most  certain  means  of  increasing  the  productiveness  of  the 
soils  formed  from  them. 

19.  The  Mica  slate  and  Gneiss  systems  are  of  unknown 
thickness,  and  consist  chiefly  of  hard  and  slaty  rocks,  crumb- 
ling slowly,  forming  poor,  thin  soils,  which  rest  on  an  imper- 
vious rock,  and  which,  from  the  height  to  which  this  formation 
generally  rises  above  the  level  of  the  sea,  are  rendered  more 


108  GENERAL   CONCLUSIONS. 

anproductive  by  an  unpropitious  climate.  They  form  extensive 
heathy  tracts  in  Perth  and  Argyle,  and  on  the  north  and  west 
of  Irehmd.  Here  and  there  only — in  the  valleys  or  sheltered 
slopes,  and  by  the  margins  of  the  lakes— spots  of  bright  green 
meet  the  eye,  and  patches  of  a  willing  soil,  fertile  in  corn. 

SECTION     IV. GENERAL     CONCLUSIONS     AS    TO     THE     RELATIONS     OF 

GEOLOGY   TO    AGRICULTURE. 

A  careful  perusal  of  the  preceding  sketch  of  the  general 
agricultural  capabilities  of  the  soils  formed  from  the  several 
classes  of  stratified  rocks,  will  have  presented  to  the  reader 
many  illustrations  of  the  facts  stated  in  the  previous  chapter. 
He  will  have  drawn  for  himself — to  specify  a  few  examples — 
the  following  among  other  conclusions  : — 

1.  That  some  formations,  like  the  new  red  sandstone,  yield 
a  soil  almost  always  productive  ;  others,  as  the  coal  measures 
and  millstone  grits,  a  soil  almost  always  naturally  unproduct- 
ive ;  and  others,  again,  like  the  mountain  limestones,  a  short 
Bweet  herbage,  grateful  to  cattle,  and  productive  of  butter 
and  cheese. 

2.  That  good — or  better  land,  at  least,  than  generally  pre- 
vails in  a  district — may  be  expected  where  two  formations,  or 
two  different  kinds  of  rock,  meet.  As  when  a  limestone  and 
a  clay  mingle  their  mutual  ruins  for  the  formation  of  a  com- 
mon soil.* 

3.  That  in  almost  every  country  extensive  tracts  ef  land,  on 
certain  formations,  will  be  found  laid  down  to  natural  grass,  in 
consequence  of  the  original  difficulty  and  expense  of  working.  Such 
are  the  Lias,  the  Oxford,  the  Weald,  the  Kimmeridge,  and  the 
London  clays.  In  raising  corn,  it  is  natural  that  the  lands 
which  are  easiest  and  cheapest  worked  should  be  first  sub- 
jected to  the  plough.  It  is  not  till  implements  are  improved, 
fikill  increased,  capital  accumulated,  and  population  presses,  that 

*  See  diagram  No.  5,  p.  95. 


ROTATIONS    OFTEN    PRESCRIBED    BY   THE    SOIL.  103 

the  heavier  lands  iu  a  country  are  rescued  from  perennial  grass, 
and  made  to  produce  that  greatly  increased  amount  of  food  for 
both  man  and  beast,  which  they  are  easily  capable  of  yielding. 

4.  That  the  rotations  adopted  in  a  district,  though  faulty, 
and,  in  the  eyes  of  improved  agriculture,  deserving  of  condem- 
nation, are  often  not  only  determined,  but  rendered  necessary 
by  the  natural  structure  of  the  country.  When  cold  clays  re- 
fuse to  bear  even  average  crops  of  any  other  kinds  than  wheat 
and  beans,  the  old  European  rotation  of  wheat,  beans,  fallow — 
which  in  this  country  has  prevailed,  in  many  places,  since  the 
times  of  the  ancient  Britons — becomes  almost  a  necessity  to  the 
farmer.  It  is  unfair  to  blame  his  rotations,  or  accuse  him  of 
prejudice  and  ignorance  in  clinging  to  them,  till  the  natural 
condition  of  the  land  has  been  altered  by  art,  so  as  to  lit  it  for 
the  profitable  growth  of  other  crops. 

The  turnip  and  barley  soils  of  Great  Britain  are  in  many  dis- 
tricts, it  may  be,  but  indifferently  farmed;  and  the  State  has 
reason  to  complain  of  much  individual  neglect  of  known  and 
certain  methods  of  iifcreasing  their  productiveness.  But  the 
great  achievement  which  British  agriculture  has  now  to  effect,  is  to 
subdue  the  stubborn  clays,  and  to  convert  them  into,  what  many  of 
them  are  yet  destined  to  become,  the  richest  corn  and  green-crop  bear- 
ing lands  in  the  kingdom. 

5.  That  there  are  larger  tracts  of  country  still — such  as  rest 
on  the  slates  of  the  Lower  Silurian  and  Cambrian  systems,  for 
example — from  which  the  efforts  of  the  enlightened  agriculturist 
have  hitherto  been  withheld,  in  consequence  of  the  apparent 
hopelessness  of  ever  bringing  them  into  profitable  culture.  Over 
these  tracts,  however,  there  are  large  portions  which  will  pay 
well  for  skilful  improvement.  Make  roads  and  drains,  bring  in 
lime,  and  manure  well.  You  will  thus  improve  the  soil,  gradu- 
ally ameliorate  the  climate,  make  modern  skill  and  improvements 
available,  obtain  a  remunerating  return  for  labor  economically 
expended,  and  for  capital  judiciously  invested,  and  you  will  at  the 
■ame  time  increase  the  power  and  the  resources  of  the  country. 


CHAPTER  VIII. 

Poor  soils  of  the  granites  and  fertile  soils  of  the  trap  rocks,  and  of  the  modem 
lavas. — Composition  of  felspar  and  hornblende. — Accumulations  of  trans- 
ported sands,  gravels,  and  claj'S. — Their  influence  on  agricultural  capa- 
bility.— Illustration  from  the  neighborhood  of  Durham. — Importance  of 
surface  or  drift  geology  to  agriculture. — General  uniformity  in  the  agri- 
cultural character  of  the  rocks  and  soils  on  geological  formations  of  the 
same  age. — Exceptions  among  the  Silurian  rocks. — Use  of  geological  maps 
in  reference  to  agriculture. 

It  was  stated  in  a  preceding  chapter  that  rocks  are  divided 
by  geologists  into  the  stratified  and  the  unstratified*  The  stra- 
tified rocks  cover  by  far  the  largest  portion  of  the  globe,  and 
form  the  great  variety  of  soils,  of  which  a  general  description 
has  just  been  given.  The  unstratified  rocks  are  of  two  kinds — 
the  granites  and  the  trap  rocks ;  and  as  a  considerable  portion 
of  the  area,  especially  of  the  northern  half,  of  our  island  is  covered 
by  them,  it  will  be  proper  shortly  to  consider  the  peculiar  char- 
acters of  each,  and  the  differences  of  the  soils  produced  from  them. 

SECTION  I. POOR   SOILS    OP   THE    GRANITES,    AND   FERTILE   SOILS   OF 

THE   TRAP   ROCKS   AND   MODERN    LAVAS. 

1.  The  Granites  consist  of  a  mixture,  in  different  proportions, 
of  three  minerals,  known  by  the  names  of  quartz,  felspar,  and 
mica.  The  latter,  however,  is  generally  present  in  such  small 
quantity,  that  in  our  general  description  it  may  be  safely  left 

*  The  unstratified  are  often  called  crystalline  rocks,  because  they  fre- 
quently have  a  glassy  appearance,  or  contain  regular  crystals  of  certain 
mineral  substances ;  often  also  igneous  rocks,  because  they  appear  all  to  have 
been  originally  in  a  melted  state,  or  to  have  been  produced  by  fire. 


POOR   GRAKITE    SOILS.  105 

out  of  view.  Granites,  therefore,  consist  chiefly  of  quartz  and 
felspar,  in  proportions  which  vary  very  much;  but  the  former, 
on  an  average,  constitutes  perhaps  from  one-third  to  one-half  of 
the  whole. 

Quartz  has  already  been  described  as  being  the  same  sub- 
stance as  flint,  or  the  silica  of  the  chemist.  When  the  granite 
decays,  this  portion  of  it  forms  a  more  or  less  coarse  silicious 
sand. 

Felspar  is  a  white,  greenish,  or  flesh-colored  mineral,  often 
more  or  less  earthy  in  its  appearance,  but  generally  hard  and 
brittle,  and  sometimes  glassy.  It  is  scratched  by  quartz,  and 
thus  is  readily  distinguished  from  it.  When  felspar  decays,  it 
forms  an  exceedingly  fine  tenacious  clay,  (pipe-clay.) 

Granite  generally  forms  hills,  and  sometimes  entire  ridges  of 
mountains.  When  it  decays,  the  rains  and  streams  wash  out 
the  fine  felspar  clay,  and  carry  it  down  into  the  valleys,  leaving 
the  quartz  sand  on  the  sides  of  the  hills.  Hence  the  soil  in  the 
bottoms  and  flats  of  granite  countries  consists  of  a  cold,  stifi; 
wet,  more  or  less  impervious  clay,  which,  though  capable  of 
much  improvement  by  draining,  often  bears  only  heath,  bog,  or 
a  poor  and  un-nutritive  pasture.  The  hUl  sides  are  either  bare, 
or  are  covered  with  a  thin,  sandy,  and  ungrateful  soil,  of  which 
little  can  be  made  without  the  application  of  much  skill  and 
industry.  Yet  the  opposite  sides  of  the  same  mountains  often 
present  a  remarkable  difference  in  this  respect;  those  which  are 
most  beaten  by  the  rains  having  the  light  clay  most  thoroughly 
washed  from  their  surfaces,  and  being  therefore  the  most  sandy 
and  barren. 

2.  The  Trap  rocks,  comprising  the  green-stones  and  basalts — 
both  sometimes  called  u"Am-stones — consist  essentially*  of  felspai 
and  hornblende  or  augite.  In  contrasting  the  trap  rocks  with 
the  granites,  it  may  be  stated  generally,  that  while  the  granites 

♦  The  reader  is  referred  for  more  precise  informatiou  to  the  Author's 
"Lectures,"  2d  edition. 

5* 


106 


COMPOSITION   OP  FELSPAR  AND  HORNBLENDE. 


consist  of  felspar  and  qua/rtz,  the  traps  consist  of  felspar  and 
hornblende  (or  augite.)  In  the  traps,  both  the  felspar  and  the 
hornblende  are  reduced,  by  the  action  of  the  weather,  to  a  more 
or  less  fine  powder,  affording  materials  for  a  soil ;  in  the  granites, 
the  felspar  is  the  principal  source  of  the  fine  earthy  matter  they 
are  capable  of  yielding.  If  we  compare  together,  therefore,  the 
chemical  composition  of  the  two  minerals,  (hornblende  and  fel- 
spar,) we  shall  see  in  what  respect  these  two  varieties  of  soil 
ought  principally  to  differ.    Thus  they  consist  respectively  of — 


Felspar. 

Hornblende 

Silica, 

65 

42 

Alumina, 

18 

14 

Potash  and  soda, 

17 

trace. 

Lime, 

trace. 

12 

Magnesia, 

do. 

14 

Oxide  of  iron, 

do. 

144 

Oxide  of  manganese. 

do. 

i 

100 


97 


A  remarkable  difference  appears  thus  to  exist,  in  chemical 
composition,  between  these  two  minerals — a  difference  which 
must  affect  also  the  soils  produced  from  them.  A  granite  soil,  in 
addition  to  the  silicious  sand,  will  consist  chiefly  of  silica,  alu- 
mina, and  potash,  derived  from  the  felspar.  A  trap  soil,  in  addi- 
tion to  the  silica,  alumina,  and  potash  from  its  felspar,  will 
generally  contain  also  much  lime,  magnesia,  and  oxide  of  iron, 
derived  from  its  hornblende.  If  the  variety  of  trap  consist 
chiefly  of  hornblende,  as  is  sometimes  the  case,  the  soil  formed 
from  it  will  derive  nearly  2^  cwt.  each  of  lune,  magnesia,  and 
oxide  of  iron,  from  every  ton  of  decayed  rock.  A  hornblende 
soil,  therefore,  contains  a  greater  number  of  those  inorganic 
substances  which  plants  require  for  their  healthy  sustenance,  and, 
therefore,  will  prove  more  generally  productive  than  a  soil  of 
decayed  felspar.  But  when  the  two  minerals,  hornblende  and 
felspar,  are  mixed  together,  as  they  are  in  the  variety  of  trap 
called  green-stone,  the  soil  formed  from  them  must  be  still  more 


FERTILITT    OF  TRAP   AND   GBEEN-STONE    SOILS.  107 

favorable  to  vegetable  life.  The  potash  and  soda,  of  which  the 
hornblende  is  nearly  destitute,  is  abundantly  supplied  by  the  fel- 
spar ;  while  the  hornblende  yields  lime  and  magnesia,  which  are 
known  to  exercise  a  remarkable  influence  on  the  progress  of 
vegetation. 

This  chemical  knowledge  of  the  nature  and  differences  of  the 
rocks  from  which  the  granite  and  trap  soils  are  derived,  explains 
several  interesting  practical  observations.     Thus  it  shows — 

a.  That  while  granite  soils,  in  their  natural  state,  may  be 
eminently  unfruitful,  trap  soils  may  be  eminently  fertile  ;  and 
such  is  actually  the  result  of  observation  and  exp<rience  in 
every  part  of  the  globe.  Unproductive  granite  soils  cover  nearly 
the  whole  of  Scotland,  north  of  the  Grampians,  as  well  as  large 
tracts  of  land  in  Devon  and  Cornwall,  and  on  the  east  and  west, 
of  Ireland.  On  the  other  hand,  fertile  trap  soils  extend  over 
thousands  of  square  miles  in  the  lowlands  of  Scotland,  and  in  the 
north  of  Ireland  ;  and  where  in  Cornwall  they  occasionally  mix 
with  the  granite  soils,  they  are  found  to  redeem  the  latter  from 
their  natural  barrenness. 

But  while  such  is  the  general  rule  in  regard  to  these  two 
classes  of  soils,  it  happens  on  some  spots  that  the  presence  of 
other  minerals  in  the  granites,  or  of  hornblende  or  mica  in 
larger  quantity  than  usual,  gives  rise  to  a  granitic  soil  of  average 
fertility,  as  is  the  case  in  the  Scilly  Isles.  In  like  manner,  the 
trap  rocks  are  sometimes,  as  in  parts  of  the  Isle  of  Skye,  so 
peculiar  in  their  composition  as  to  condemn  the  land  to  almost 
hopeless  infertility. 

b.  Why  in  some  districts  the  decayed  traps,  under  the  local 
names  of  Rotten  rock,  Marl,  &c.,  are  dug  up,  and  applied  with 
advantage,  as  a  top-dressing,  to  other  kinds  of  land.  They 
afford  supplies  of  lime,  magnesia,  &c.,  of  which  the  soils  they 
are  found  to  benefit  may  be  naturally  deficient.  And  as,  by 
admixture  with  the  decayed  trap,  the  granitic  soils  of  Cornwall 
are  known  to  be  improved  in  quality,  so  an  admixture  of  decayed 


108  MMINQ   OF   TRAP   SOILS. 

granite  with  many  trap  soils,  were  it  readily  accessible,  might 
add  to  the  fertility  of  the  latter  also. 

c.  Why  the  application  of  lime  in  certain  trap  districts  adds 
nothing  to  the  fertility  of  the  land.  The  late  Mr.  Oliver  of 
Lochend  informed  me  that  he  had  never  known  a  case  in  which 
the  application  of  lime  within  five  miles  of  Edinburgh  had  done 
any  good.  This  he  accounted  for  f»om  the  vast  number  of 
oyster  shells  which  are  mixed  with  the  town  dung  laid  on  by  the 
Edinburgh  farmers.  Another  important  reason,  however,  is  the 
abundance  of  lime  contained  in  the  trap  rocks  from  which  the 
soils  are  formed,  and  of  which  they  contain  so  many  fragments. 
A  piece  of  decaying  trap  I  lately  picked  up  on  the  north  side 
of  the  Pentland  hills,  on  the  farm  of  Swanstone,  was  found  in 
my  laboratory  to  contain  as  much  as  16  per  cent  of  carbonate 
of  lime. 

d.  Why,  as  in  many  parts  of  the  counties  of  Ayr  and  Fife, 
the  application  of  lime  is  found  to  be  useful  when  the  trap  soils 
are  first  broken  up  or  reclaimed,  but  to  produce  little  sensible 
benefit  for  twenty  or  thirty  years  afterwards,  however  frequently 
applied.  In  these  cases  the  lime  has  been  washed  out  of  the 
surface  soil,  and  from  the  thoroughly  decayed  parts  of  the  trap, 
so  that,  when  first  broken  up,  lime  is  necessary  to  supply  the 
deficiency.  But  the  constant  turning  up  of  the  soil  by  the  after- 
cultivation  exposes  fresh  portions  of  trap  to  the  air,  the  decay 
of  which  annually  supplies  a  quantity  of  lime  to  the  soil  from  the 
rocky  fragments  themselves,  and  renders  further  artificial  appli- 
cations less  necessary.  I  have  picked  up  a  piece  of  decaying 
trap,  of  which  the  outer  portion  contained  scarcely  any  lime, 
while  the  central  kernel  contained  a  large  proportion.  The 
plough  and  harrow  break  up  such  decaying  masses,  and  expose 
the  undecomposed  kernels  to  the  weathering  action  of  the  atmo- 
sphere, and  to  the  roots  of  the  growing  crops. 

3.  The  Lavas  which  often  cover  large  tracts  of  country,  where 
active  or  extinct  volcanoes  exist,  are  composed  essentially  of  the 
same  mineral  substances  a9  the  trap  rocks.    These  latter,  indeed. 


APPARENT  DIFFICULTIES.  109 

are  in  general  only  lavas  of  a  more  ancient  date.  Like  the 
traps,  the  lavas  not  unfrequently  abound  in  hornblende  or  augite, 
and  consequently  in  lime.  They  also  crumble,  with  various 
degrees  of  rapidity,  when  exposed  to  the  air,  and  in  Italy  and 
Sicily  often  form  soils  of  the  most  fertile  description.  Like  the 
traps  also,  when  in  a  decayed  state,  they  may  be  advantageously 
employed  for  the  improvement  of  less  fruitful  soils.  In  St, 
Michael's,  one  of  the  Azores,  the  natives  pound  the  volcanic 
matter  and  spread  it  on  the  ground,  where  it  speedily  becomes 
a  rich  mould,  capable  of  bearing  luxuriant  crops. 

SECTION  II. OF   THE    SUPERFICIAL  ACCUMULATIONS  OF  TRANSPORTED 

MATERIALS    ON   DIFFERENT   PARTS   OF  THE    EARTH'S    SURFACE,  AND 
THEIR   RELATIONS    TO    THE    SOIL. 

It  is  necessary  to  guard  the  reader  against  disappointment 
when  he  proceeds  to  examine  the  relations  which  exist  between 
the  soils  and  the  rocks  on  which  they  lie,  or  to  infer  the  quality 
of  the  soil  from  the  known  nature  of  the  rock  on  which  it  rests 
— in  conformity  with  what  has  been  above  laid  down — by  ex- 
plaining another  class  of  geological  appearances,  which  present 
themselves  not  only  in  our  own  country,  but  in  almost  every 
other  part  of  the  globe. 

The  unlearned  reader  of  the  preceding  section  and  chapter 
may  say — I  know  excellent  land  resting  upon  the  granites,  fine 
turnip  soils  on  the  Oxford  or  London  clays,  tracts  of  fertile  fields 
on  the  coal  measures,  and  poor  gravelly  farms  on  the  boasted 
new  red  sandstone  :  I  have  no  faith  in  theory — I  can  have  none 
in  theories  which  are  so  obviously  contradicted  by  natural  ap- 
pearances. Such,  it  is  to  be  feared,  is  the  hasty  mode  of  rea- 
soning among   too  many  locally*  excellent  practical  men — 

*  By  locally  excellent,  I  mean  those  who  are  the  best  possible  farmers  on 
their  own  districts  and  after  their  own  way,  but  who  would  fail  in  other 
districts  requiring  other  methods.  To  the  possessor  of  agricultural  princi- 
ples^ the  modifications  required  by  difference  of  crop,  soil,  and  climate^ 


110  LOOSE,    TRANSPORTED   MATERIALS. 

familiar,  it  may  be,  with  many  useful  and  important  facts,  but 
untaught  to  look  through  and  beyond  isolated  facts  to  the 
principles  on  which  they  depend. 

Every  one  who  has  lived  long  on  the  more  exposed  shores  of 
our  island,  has  seen  that,  when  the  weather  is  dry,  and  the  sea- 
'  winds  blow  strong,  the  sands  of  the  beach  are  carried  inland  and 
spread  over  the  soil,  sometimes  to  a  considerable  distance  from 
the  coast.  In  some  countries  this  sand-drift  takes  place  to  a 
very  great  extent,  travels  over  a  great  stretch  of  country,  and  " 
gradually  swallows  up  large  tracts  of  fertile  land,  and  converts 
them  into  sandy  deserts. 

Again,  most  people  are  familiar  with  the  fact,  that  during 
periods  of  long  continued  rain,  when  the  rivers  are  flooded  and 
overflow  their  banks,  they  not  unfrequently  bear  with  them  loads 
of  sand  and  gravel,  which  they  carry  far  and  wide,  and  strew  at 
intervals  over  the  surface  soil. 

So  the  annual  overflowings  of  the  Nile,  the  Ganges,  the  Mis- 
sissippi, and  the  river  of  the  Amazons,  gradually  deposit  accu- 
mulations of  soil  over  surfaces  of  great  extent ; — and  so  also  the 
bottoms  of  most  lakes  are  covered  with  thick  beds  of  sand,  gravel 
and  clay,  which  have  been  conveyed  into  them  from  the  higher 
grounds  by  the  rivers  which  flow  into  them.  Over  the  bottom 
of  thie  sea  also,  the  ruins  of  the  land  are  spread.  Torn  by  the 
waves  from  the  crumbling  shore,  or  carried  down  from  great 
distances  by  the  rivers  which  lose  themselves  in  the  sea,  they 
form  beds  of  mud,  or  banks  of  sand  and  gravel  of  great  extent, 
which  cover  and  conceal  the  rocks  on  which  they  lie. 

To  these  and  similar  agencies,  a  large  portion  of  the  existing 
dry  land  of  the  globe  has  been,  and  is  still,  exposed.  Hence, 
in  many  places,  the  rocks  and  the  soils  naturally  derived  from 
them  are  buried  beneath  accumulated  heaps  of  layers  of  sand, 
gravel,  and  clay,  which  have  been  brought  from  a  greater  or 
less  distance,  and  which  have  not  unfrequently  been  derived 

readily  suggest  themselves,  where  the  mere  practical  man  ia  bewildered 
disheartened,  and  in  despair. 


CIRCUMSTANCES  TO  BE  CONSIDERED.  Ill 

from  rocks  of  a  totally  different  kind  from  those  of  the  districts 
in  which  they  are  now  found.  On  these  accumulations  of  trans- 
ported materials,  a  soil  is  produced  which  often  has  no  relation 
in  its  characters  to  the  rocks  which  cover  the  country,  and  the 
nature  of  which  soils,  therefore,  a  familiar  acquaintance  with 
the  rocks  on  which  they  immediately  rest  would  not  enable  us  to 
predict. 

To  this  cause  is  due  that  discordance  between  the  first  indi- 
cations of  geology,  as  to  the  origin  of  soils  from  the  rocks  on 
which  they  rest,  and  the  actually  observed  characters  of  those 
soils  in  certain  districts — of  which  discordance  mention  has  been 
made  as  likely  to  awaken  doubt  and  distrust  in  the  mind  of  the 
less  instructed  student,  in  regard  to  the  predictions  of  agricul- 
tural geology.  There  are  several  circumstances,  however,  by 
which  the  careful  observer  is  materially  aided  in  endeavoring  to 
understand  what  the  nature  of  the  soils  is  hkely  to  be  in  any 
given  district,  and  how  they  ought  to  be  treated  even  when  the 
subjacent  rocks  are  thus  overlaid  by  masses  of  drifted  materials. 
Thus— 

1.  It  not  unfrequently  happens  that  the  materials  brought 
from  a  distance  are  more  or  less  mixed  up  with  the  fragments 
and  decayed  matter  of  the  rocks  which  are  native  to  the  spot, 
— so  that,  though  modified  in  quality,  the  soil  nevertheless 
retains  the  general  characters  of  that  which  is  formed  in  other 
places  from  the  decay  of  these  rocks  alone. 

2.  Where  the  formation  is  extensive,  or  covers  a  large  area, 
— as  the  new  red  sandstones  and  coal  measures  do  in  this  coun- 
try, the  mountain  limestones  in  Ireland,  and  the  granites  in  the 
north  of  Scotland, — the  transported  sand,  gravel,  or  clay, 
strewed  over  one  part  of  the  formation,  has  not  unfrequently 
been  derived  from  the  rocks  of  another  part  of  the  same  for- 
mation ;  so  that,  after  all,  the  soils  may  be  said  to  be  produced 
from  the  rocks  on  which  they  rest,  and  may  be  judged  of  from 
the  known  composition  of  these  rocks. 

3.  Or  if  not  from   the  rocks  of  the  same  formation,  they 


112  SOILS   OVERLAP  THEIR   NATURAL   LIMITS. 

have  most  frequently  been  derived  from  those  of  a  neighboring 
formation — ^from  rocks  which  are  to  be  found  at  no  great  distance 
geologically,  and  generally  on  higher  ground.  Thus  the  ruins 
of  the  millstone-grit  rocks  are  in  this  country  often  spread  over 
the  surface  of  the  coal  measures — of  these,  again,  over  the 
magnesian  limestone — of  the  latter  over  the  new  red  sand- 
stone, and  so  on.  The  effect  of  this  kind  of  transport  of  the 
loose  materials  upon  the  character  of  the  soils  is  merely  to 
overlap,  as  it  were,  the  edges  of  one  formation  with  the  proper 
soils  of  the  formations  that  adjoin  it,  in  the  particular  direction 
from  which  the  drifted  materials  are  known  to  have  come. 

It  appears,  therefore,  that  the  occurrence  on  certain  spots,  or 
tracts  of  country,  of  soils  that  have  no  apparent  relation  to  the 
rocks  on  which  they  immediately  rest,  tends  in  no  way  to 
throw  doubt  upon,  to  discredit  or  to  disprove,  the  conclusions 
drawn  from  the  more  general  facts  and  principles  of  geology. 
It  is  still  generally  true  that  soils  are  derived  from  the  rocks  ou 
which  they  rest.  The  exceptions  are  local,  and  the  difficulties 
which  these  local  exceptions  present,  require  only  from  agricul- 
tural geologists  a  more  careful  study  of  the  structure  of  each 
district — of  the  direction  of  the  highlands — the  nature  of  the 
slopes — the  course  and  width  of  the  valleys — and  the  extent  of 
the  plains, — before  they  pronounce  a  decided  opinion  as  to  the 
degree  of  fertility  which  the  soil  either  naturally  possesses,  or 
by  skilful  cultivation  may  be  made  to  attain. 

It  is  not  to  be  denied,  however,  that  the  practical  importance 
of  these  local  exceptions  is  becoming  every  day  more  manifest, 
and  the  necessity  more  apparent  for  a  careful  recording  and 
mapping  of  them  in  the  interests  of  agriculture.  Riding  over 
the  country,  for  example,  due  north  from  the  city  of  Durham, 
a  distance  of  about  three  miles,  till  we  are  stopped  by  a  bend 
of  the  river  Wear,  the  superficial  covering,  so  far  as  it  can  be 
seen,  is  represented  by  the  subjoined  section. 


i 

DRIFT   COVERING    NEAR   DURHAM. 

No.  7. 

Kimbles. 
Red  Hills.           worth. 

y -^:::i>>-j-7— s,__             Bishop's 

/'  i-^^.i  .'•  .':T.  '»*•'-.  r^^~^C~^^v^   Grange. 

,  ^ 

'-y^^r^^-r/VVy^  /  /      '/7V~T^^ 

113 


1.  Yellow  unstratified  hard  clay  with  small  stones  and 
boulders,  forming  cold  impervious  clay  soils,  3  to  40  feet. 

2.  Yellow  sand,  loose,  with  fragments  of  drifted  coal  and 
sandstone  gravel  and  boulders,  forming  potato,  barley,  and  light 
turnip  soils,  10  to  100  feet. 

3.  Blue  unstratified  clay,  with  boulders — often  wanting — iO 
to  30  feet. 

4.  The  coal  measures  lying  beneath. 

All  the  country  being  covered,  as  this  section  represents, 
with  from  30  to  120  feet  of  superficial  sands  and  clays,  it  is 
obvious  that  it  can  be  of  comparatively  little  use  to  me  to  know 
that  the  sandstones  and  shales  of  the  coal  measures  lie  far 
below  ;  and  though  I  know  that  the  sands  and  clays  are  all 
derived  from  the  crumbled  beds  of  the  coal  measures,  yet  they 
give  me  no  information  respecting  the  sandy  nature  of  the  soils 
near  Kimblesworth,  or  that  they  are  cold  and  clayey  about 
Bishop's  Grange.  The  nature  of  the  soil  in  each  portion  of  the 
district — and  the  same  is  true  of  a  large  portion  of  the  county 
of  Durham — depends  upon  whether  the  clay  or  the  sand  comes 
to  the  surface.  This  can  only  be  shown  upon  special  maps,  rig- 
orously prepared  for  the  purpose  ;  and  these  the  progress  of 
scientific  agriculture  will  soon  render  indispensable. 


SECTION  III. GENERAL  UNIFORMITY  IN  THE  AGRICULTURAL  CHAR- 
ACTER OF  THE  ROCKS  AND  SOILS  ON  GEOLOGICAL  FORMATIONS  OP 
THE    SAME    AGE. 

And  yet  there  is  a  wonderful  degree  of  general  uniformity  in 


114  UNIFORMITT   IN   THE   AGRICULTURAL   CHARACTER 

the  mineral  character  and  agricultural  capabilities  of  the  same 
geological  formation  in  different  countries,  even  v/heu  they  lie  at 
great  distances  from  each  other.  I  have  already  alluded,  for 
example,  in  a  preceding  chapter,*  to  the  natural  dryness  of  the 
belt  of  chalk  which  runs  along  the  Atlantic  border  of  the 
United  States.  The  scarcity  of  water  experienced  by  those 
who  reside  upon  it  is  often  great.  Every  one  knows  that  the 
same  is  true  of  our  own  chalk  region  in  England,  and  that  this 
very  materially  affects  its  agricultural  capabilities.  It  is  famil- 
iar to  every  one  also,  that  in  very  many  places  wells  are  sunk 
through  it  with  the  view  of  reaching  water,  and  that  in  London 
great  depths  are  gone  to,  and  at  a  vast  expense,  through  the 
London  clay  and  the  chalk,  before  water  can  be  obtained.  In 
the  Paris  basin  the  chalk  is  equally  dry  ;  and  there  are  very 
few  who  have  not  read  of  the  remarkably  deep  well  at  Grenelle 
in  the  neighborhood  of  Paris,  which,  hke  the  less  profound 
London  wells,  has  been  sunk  to  the  sands  below  the  chalks,  and 
with  similar  success. 

So,  in  the  remote  State  of  Alabama,  on  this  formation,  water 
is  only  to  be  obtained  by  sinking  through  the  chalk  ;  and  there 
also  this  circumstance  modifies  in  a  wonderful  degree  the  gene- 
ral dispositions  of  rural  economy.  Three  years  ago  there  were 
already  about  500  wells  in  that  State,  sunk  to  a  depth  of  from 
400  to  600  feet,  there  being  one  generally  upon  each  plantation. 
And  thus,  while  the  climate  there,  as  elsewhere,  determines  the 
general  character  of  the  vegetable  produce,  and  what  kind  of 
plants  under  the  meteorological  conditions  can  arrive  at  perfec- 
tion, yet  the  geological  structure  determines,  and  enables  us  to 
judge  beforehand,  to  a  certain  extent,  whether  or  not  any  crops 
shall  be  able  to  grow  at  all,  and  of  the  kind  of  plants  suitable 
to  the  climate,  .which  can  be  profitably  cultivated,  under  the 
circumstances  of  soil  and  dryness,  which  that  geological  structure 
implies.  ^ 

*  Seo  the  diagram  in  p.  91. 


OF    SOILS    OF  THE    SAME    FORMATION.  115 

I  may  here  remark,  that,  in  this  case  of  Alabama,  the  geo- 
logical structure  determines  more.  In  such  a  climate,  and  with 
a  soil  so  naturally  arid,  abundant  water  is  indispensable  ;  but 
this  can  only  be  obtained  by  deep  boring,  performed  at  a  great 
expense.  The  geological  conditions,  therefore,  confine  the  pos- 
sibility of  cultivation  to  men  of  large  means,  and,  in  present 
circumstances  at  least,  necessarily  exclude  all  petty  farming  and 
the  subdivision  of  the  land  into  small  holdings.  They  deter- 
mine, in  other  words,  the  social  condition  of  the  people.  This 
single  illustration  is  enough  of  itself  to  satisfy  any  impartial 
person  of  the  close  genei'al  relation  which  exists  between  the 
geological  character  and  the  agricultural  capability  of  a  coun- 
try, and  of  the  broad  general  deductions  in  regard  to  its  possible 
future  prosperity — in  a  rural  sense — which  may  be  drawn  from 
a  knowledge  of  its  geology.  I  believe  it  is  partly  under  the 
influence  of  this  conviction  that  the  Senate  and  Congress  of  the 
United  States  have  so  often  and  so  cordially  voted  large  sums 
of  money  for  the  purpose  of  investigating  and  mapping  the 
main  geological  features  of  the  new  States  and  territories  which 
from  time  to  time  have  been  admitted  into  the  Union. 

Geological  maps,  such  as  those  now  referred  to,  indicate  with 
more  or  less  precision  the  extent  of  country  over  which  the 
chalk,  the  red  sandstone,  the  granites,  &c.,  are  found  immedi- 
ately beneath  the  loose  materials  on  the  surface.  Such  maps, 
therefore,  are  of  great  value  in  indicating  also  the  general  qual- 
ity of  the  soils  over  the  same  districts.  It  may  be  true,  as  I 
have  above  explained,  that  here  and  there  the  natural  soils  are 
masked  or  buried  by  transported  materials — yet  the  political 
economist  may,  nevertheless,  with  safety  estimate  the  general 
agricultural  capabilities  and  resources  of  a  couniry  by  the  study 
of  its  geological  structure — the  capitalist  judge  in  what  part  of 
it  he  is  likely  to  meet  with  an  agreeable  or  profitable  investment 
— and  the  practical  farmer  in  what  country  he  may  expect  to 
find  land  that  will  best  reward  his  labors,  that  will  admit  of 
the  kind  of  culture  to  which  he  is  most  accustomed,  or,  by  the 


116  GEOLOGY  NOT  PERFECT. 

application  of  better  methods,  will  manifest  the  greatest  agri- 
cultural improvement. 

There  are  many  cases  also  in  which  geology,  leaving  the  hum- 
bler task  of  explaining  why  certain  regions  exhibit,  or  are  capa- 
ble of  exhibiting,  singular  natural  fertility,  or  the  reverse, 
advances  to  the  higher  gift  of  prediction.  United  theory  and 
observation  enable  it  not  only  to  point  out  where  rich  and 
desirable  lands  are  sure  to  be  found — to  inform  the  statesman 
as  to  the  true  value  of  regions  still  wild  and  neglected — to 
direct  the  agricultural  emigrant  in  the  choice  of  new  homes — 
but  looking  far  into  the  future,  to  specify  also  the  kind  of  popu- 
lation and  the  processes  of  industry  which  will  hereafter  prevail 
upon  it — the  comparative  comfort,  wealth,  numbers,  and  even 
morality,  of  its  future  people. 

That  there  are  certain  cases  in  which  geology  finds  herself  at 
fault,  or  her  general  deductions  unsupported  by  the  reality,  is 
only  a  proof  that  it  is  a  part  of  human  science,  rapidly  pro- 
gressive, but  still  full  of  imperfections. 


CHAPTER  IX. 

Of  the  physical,  chemical,  ai  d  botanical  relations  of  soils. — Physical  proper- 
ties.—  Density,  absorbent,  and  evaporative  powers,  capillary  action, 
shrinkage,  absorption  of  moisture  from  tlie  air,  and  of  heat  from  the  sun. 
— Functions  of  soils  in  reference  to  vegetation. — Chemical  composition  and 
analysis  of  soils. — Comparative  composition  of  certain  fertile  and  barren 
soils. — Importance  of  certain  forms  of  organic  matter  to  the  fertility  of  a 
soil. — The  black  earth  of  central  Russia. — Direct  relation  between  the 
character  of  the  soil  and  the  kind  of  plants  that  naturally  grow  upon  it. 

Soils  formed,  as  we  have  described,  from  the  ruins  of  crrnnb- 
led  rocks,  more  or  less  sorted  and  drifted  by  water,  possess 
three  classes  of  properties,  intimately  related  to  each  other, 
and  to  their  special  agricultural  value.  These  are  their  phy- 
sical, cJiemical,  and  botanical  properties.  A  brief  consideration 
of  these  will  form  the  subject  of  the  present  chapter. 

SECTION    I. OF   THE    PHYSICAL   PROPERTIES    OF    SOILS. 

1°.  Density. — Some  soils  are  heavier  and  denser  than  others, 
sands  and  marls  weighing  most  and  dry  peaty  soils  the  least. 
This  density  is  of  so  much  practical  importance,  that  treading 
with  sheep  and  other  stock  is  resorted  to  in  many  districts, 
with  the  view  of  rendering  the  land  more  solid  ;  or  heavy 
rollers  are  passed  over  it,  to  prepare  a  firm  seed-bed  for  the 
corn.  Also,  in  reclaiming  peaty  soils,  it  is  found  highly  bene- 
ficial to  increase  their  density  by  a  covering  of  clay  or  sand,  or, 
as  in  Ireland,  of  limestone  gravel. 

2**.  Absorption  of  water. —  Again,  some  soils  absorb  the 
rains  that  fall,  and  retain  them  in  larger  quantity  and  for  a 
longer  period  than  others.  Strong  clays  absorb  and  retain 
nearly  three  times  as  much  water  as  sandy  soils  do,  while  peaty 


118  PHYSICAL   PROPERTIES   OF    SOILS. 

Boils  absorb  a  still  larger  proportion.  Hence  the  more  fre- 
quent necessity  for  draining  clayey  than  sandy  soils  ;  and  hence 
also  the  reason  why,  in  peaty  land,  the  drains  must  be  kept 
carefully  open,  in  order  that  the  access  of  springs  and  of  other 
water  from  beneath  may  be  as  much  as  possible  prevented. 

3°.  The  capillary  action  of  soils  also  dififers.  Some,  when 
immersed  in  water,  will  become  moist,  or  attract  the  water 
upwards  for  10  or  12  inclies,  some  as  many  as  16  or  18  inches, 
above  the  surface  of  the  water.  This  property  is  of  great 
importance  in  reference  to  the  growth  of  plants — to  the  rising 
of  water  to  the  surface  of  land  which  rests  upon  a  wet  subsoil 
—  to  the  necessity  for  thorough  drainage — to  the  general 
warmth  of  the  soil,  and  so  on. 

4°.  Evaporative  power. — When  dry  weather  comes,  soils  lose 
water  by  evaporation  with  different  degrees  of  rapidity.  In 
this  way  a  silicious  sand  will  give  off  the  same  weight  of  water, 
in  the  form  of  vapor,  in  one-third  of  the  time  necessary  to 
evaporate  it  from  a  stiff  clay,  a  peat,  or  a  rich  garden  mould, 
when  all  are  equally  exposed  to  the  air.  Hence  the  reason 
why  plants  are  so  soon  burned  up  in  a  sandy  soil.  Not  only 
do  such  soils  retain  less  of  the  rain  that  falls,  but  that  which  is 
retained  is  also  more  speedily  dissipated  by  evaporation. 
When  rains  abound,  however,  or  in  very  moist  seasons,  these 
same  properties  of  sandy  soils  enable  them  to  dry  quickly,  and 
thus  to  sustain  a  luxuriant  vegetation  at  a  time  when  plants 
will  perish  on  clay  lands  from  excess  of  moisture. 

5".  Shrinkage. — In  drying  under  the  influence  of  the  sun, 
soils  shrink  in,  and  thus  diminish  in  bulk,  in  proportion  to  the 
quantity  of  clay  or  of  peaty  matter  they  contain.  Sand 
scarcely  diminishes  at  all  in  bulk  by  drying,  but  peat  shrinks 
one-fifth  in  bulk,  and  strong  agricultural  clay  nearly  as  much. 
The  roots  are  thus  compressed  and  the  air  excluded  from  them, 
especially  in  the  hardened  clays,  in  very  dry  weather,  and  thu3 
the  plant  is  placed  in  a  condition  unfavorable  to  its  growth. 
Hence  the  value  of  proper  admixtures  of  sand  and.  clay.    By 


TEMPERATURE    OF   A    SOIL.  119 

the  latter  (the  clay)  a  sufficient  quantity  of  moisture  is  re- 
tained, and  for  a  sufficient  length  of  time  ;  while  by  the  former 
the  roots  are  preserved  from  compression,  and  a  free  access  of 
the  air  is  permitted. 

1°.  Absorption  of  moisture  from  the  air. — In  the  hottest  and 
most  drying  weather,  the  soil  has  seasons  of  respite  from  the 
scorching  influence  of  the  sun.  During  the  cooler  season  of 
the  night,  even  when  no  perceptible  dew  falls,  it  has  the  power 
of  again  extracting  from  the  air  a  portion  of  the  moisture  it 
had  lost  during  the  day.  Perfectly  pure  sand  possesses  this 
power  in  the  least  degree  ;  it  absorbs  little  or  no  moisture 
from  the  air.  A  stiff  day,  on  the  other  hand,  will,  in  a  single 
night,  absorb  sometimes  a  dOth  part  of  its  oicn  weight,  and  a  dry 
peat  as  much  as  a  12th  of  its  iceight ;  and,  generally,  the  quan- 
tity thus  drunk  in,  by  soils  of  various  qualities,  is  dependent 
upon  the  proportions  of  clay  and  veg^etable  matter  they  seve- 
rally contain.  We  cannot  fail  to  perceive  from  these  facts, 
how  much  the  productive  capabilities  of  a  soil  are  dependent 
upon  the  proportions  in  which  its  different  earthy  and  vegetable 
constituents  are  mixed  together. 

*I°.  The  temperature  of  a  soil,  or  tlie  degree  of  warmth  it 
is  capable  of  attaining  under  the  influence  of  the  sun's  rays, 
materially  affects  the  progress  of  vegetation.  Every  gardener 
knows  how  much  bottom  heat  forces  the  growth,  especially  of 
young  plants  ;  and  wherever  a  natural  warmth  exists  in  the 
soil,  independent  of  the  sun,  as  in  the  neighborhood  of  vol- 
canoes, there  it  exhibits  the  most  exuberant  fertility.  One 
main  influence  of  the  sun  in  spring  and  summer  is  dependent 
upon  its  power  of  thus  warming  the  soil  around  the  young 
roots,  and  rendering  it  propitious  to  their  rapid  growth.  But 
the  sun  does  not  warm  all  soils  alike — some  become  much 
hotter  than  others,  though  exposed  to  the  same  sunshine. 
When  the  temperature  of  the  air  in  the  shade  is  no  higher 
than  60°,  or  10°,  a  dry  soil  may  become  so  warm  as  to  raise  the 
thermometer  to  90°  or  100°.    Mrs.  Ellis  states,  that  amoug 


120  INFLUENCE    OF   THE   SUN. 

the  Pyrenees  the  rocks  actually  smoke  after  rain,  under  the 
influence  of  the  summer  sun,  and  become  so  hot  that  you  can- 
not sit  down  upon  them.  In  Central  Australia,  where  the 
thermometer  is  sometimes  as  high  as  132°  F.  in  the  shade,  and 
157°  in  the  sunshine,  the  ground  beco'^  js  so  hot  that  it  kindles 
matches  that  fall  on  it,  and  burns  tue  skin  off  the  dogs'  feet. 
In  wet  soils  the  temperature  rises  more  slowly,  and  rarely 
attains  the  same  height  as  in  a  dry  soil  by  10°  or  15°.  Hence 
it  is  strictly  correct  to  say,  that  wet  soils  are  cold ;  and  it  is 
easy  to  understand  how  this  coldness  is  removed  by  perfect 
drainage.*  Dry  sands  and  clays,  and  blackish  garden  mould, 
become  warmed  to  nearly  an  equal  degree  under  the  same  sun  ; 
brownish-red  soils  are  heated  somewhat  more,  and  dark-colored 
peaty  soils  the  most  of  all.  It  is  probable,  therefore,  that  the 
presence  of  dark-colored  vegetable  matter  renders  the  soil 
more  absorbent  of  heat  from  the  sun,  and  that  the  color  of  the 
dark-red  marls  of  the  new  and  old  red  sandstones  may,  in 
some  degree,  aid  the  other  causes  of  fertility  in  the  soils  which 
they  produce. 

In  reading  the  above  observations,  the  practical  reader  can 
hardly  fail  to  have  been  struck  with  the  remarkable  similarity 
in  physical  properties  between  stiff  clay  and.  peaty  soils. 
Both  retain  much  of  the  water  that  falls  in  rain,  and  both 
part  with  it  slowly  by  evaporation.  Both  contract  mudh  in 
drying,  and  both  absorb  moisture  readily  from  the  air,  in  the 
absence  of  the  sun.  In  this  similarity  of  properties  we  see 
not  only  why  the  first  steps  in  improving  both  kinds  of  soil 
must  be  very  nearly  the  same,  but  why,  also,  a  mixture  either 
of  clay  or  of  vegetable  matter  will  equally  impart  to  a  sandy 
soil  many  of  those  elements  of  fertility — of  which  they  are 
alike  possessed. 

*  See  the  succeeding  Chapter* 


CHEMICAL   COMPOSITION   AND   ANALYSIS    OF   SOILS.  121 


SECTION    II.  —  OF    THE    CHEMICAL    COMPOSITION   AND    ANALYSIS    OF 

SOILS. 

Soils  perform  at  least  three  functions  in  reference  to  vege- 
tation. They  serve  as  a  basis  in  which  plants  may  fix  their 
roots  and  sustain  themselves  in  their  erect  position — they  supply 
food  to  vegetables  at  every  period  of  their  growth — and  they 
are  the  medium  in  which  many  chemical  changes  take  place, 
that  are  essential  to  a  right  preparation  of  the  various  kinds 
of  food  which  the  soil  is  destined  to  yield  to  the  growing 
plant. 

We  have  spoken  of  soils  as  consisting  chiefly  of  sand,  lime, 
and  clay,  with  certain  saline  and  organic  substances  in  smaller 
and  variable  proportions.  But  the  study  of  the  ash  of  plants 
(see  chap,  iv.)  shows  us  that  a  fertile  soil,  besides  its  organic 
matter,  must  of  necessity  contain  an  appreciable  quantity  of 
twelve  or  fourteen  different  mineral  substances,  which,  in  most 
cases,  exist  in  greater  or  less  relative  abundance  in  the  ash  both 
of  wild  and  of  cultivated  plants. 

Two  well-known  geological  facts  lead  to  precisely  the  same 
conclusion.  We  have  seen  that  the  soils  formed  from  the  un- 
stratified  rocks — the  granites  and  the  traps — while  they  each 
contain  certain  earthy  substances  in  proportions  peculiar  to 
themselves,  yet  contain  also  in  general,  especially  the  trap 
soils,  a  trace  of  most  of  the  other  kinds  of  matter  which  are 
found  in  the  ash  of  plants.  Again,  it  is  equally  certain  that 
the  stratified  rocks  are  only  the  more  or  less  slowly  accumu- 
lated fragments  and  ruins  of  more  ancient  stratified  or  unstra- 
tified  masses,  which,  under  various  agencies,  have  gradually 
crumbled  to  dust,  been  strewed  over  the  surface  in  alternate 
layers,  and  have  afterwards  again  consolidated.  The  reader 
will  readily  grant,  therefore,  that  in  all  rocks,  and  consequently 
in  all  soils,  traces  of  every  one  of  these  substances  may  gen©-; 
rally  be  presumed  to  exist. 
6 


ttS  GENERAL   COMPOSITION    OF    SOILS. 

Actual  chemical  analysis  confirms  these  deductions  in  regard 
to  the  composition  of  soils.  It  shows  that,  in  most  soils,  the 
presence  of  all  the  constituents  of  the  ash  of  plants  may  be  de- 
tected, though  in  very  variable  and  sometimes  in  very  minute 
proportions  ;  and,  following  up  its  investigations  in  regard  to 
the  effect  of  this  difference  in  their  proportions,  it  establishes 
certain  other  points  of  the  greatest  possible  importance  to  agri- 
cultural practice.     Thus,  it  has  found,  for  example — 

1.  That  as  a  proper  adjustment  of  the  proportions  of  clay, 
sand,  and  vegetable  matter,  is  necessary  in  order  that  a  soil 
may  possess  the  most  favorable  physical  properties,  so  the 
mere  presence  of  the  various  kinds  of  food,  organic  and  inor- 
ganic, in  a  soil,  is  not  sufficient  to  make  it  productive  of  a  given 
crop,  but  that  they  must  be  present  in  such  quantity  that  the 
plant  shall  be  able  readily — at  the  proper  season,  and  within 
the  time  usually  allotted  to  its  growth — to  obtain  an  adequate 
supply  of  each. 

Thus  a  soil  may  contain,  on  the  whole,  far  more  of  a  given 
ingredient,  such  as  potash,  soda,  and  lime,  than  the  crop  we 
have  sown  may  require,  and  yet,  being  diffused  through  a  large 
quantity  of  earth,  the  roots  may  be  unable  to  collect  this  sub- 
stance fast  enough  to  supply  the  wants  of  a  rapidly  growing 
plant.  To  such  a  soil  it  will  be  necessary  to  add  a  further  por- 
tion of  what  the  crop  requires. 

Again,  a  crop  of  winter  wheat,  which  remains  nine  or  ten 
months  in  the  field,  has  much  more  leisure  to  collect  from  the 
soils  those  substances  which  are  necessary  to  its  growth  than  a 
crop  of  barley,  which  in  cold  climates  like  that  of  Sweden  is 
only  from  6  to  7|  weeks  in  the  soil,  and  which  in  warm 
countries  like  Sicily  may  be  reaped  twice  in  the  year.  Thus  a 
soil  which  refuses  to  yield  a  good  crop  of  the  quick-growing 
barley  may  readily  nourish  a  crop  of  slow-growing  wheat. 

2.  That  when  a  soil  is  particularly  poor  in  certain  of  these 
substances,  the  valuable  cultivated  corn  crops,  grasses,  and 


USB   OF   CHEMICAL  ANALYSIS  TO   AGRICULTURE.  123 

trees,  refuse  to  grow  upon  them  in  a  healthy  manner,  and  to 
yield  remunerating  returns.     And, 

3.  That  when  certain  other  substances  are  present  in  too 
great  abundance,  the  soil  is  rendered  equally  unpropitious  to 
the  most  important  crops. 

In  these  facts  the  intelligent  reader  will  perceive  the  founda- 
tion of  the  varied  applications  to  the  soil  which  are  everj'where 
made  under  the  direction  of  a  skilful  practice — and  of  the  diffi- 
culties which,  in  many  localities,  lie  in  the  way  of  bringing  the 
land  into  such  a  state  as  shall  fit  it  readily  to  supply  all  the 
wants  of  those  kinds  of  vegetables  which  it  is  the  special  ob- 
ject of  artificial  culture  easily  and  abundantly  to  raise. 

Chemical  analysis  is  a  difficult  art — one  which  demands  much 
chemical  knowledge,  as  well  as  skill  in  chemical  practice, 
(manipulation,  as  it  is  called,)  and  calls  for  both  time  and  per- 
severance— if  valuable,  trustworthy,  and  minutely  correct  results 
are  to  be  obtained.  I  believe  it  is  only  by  aiming  after  such 
minutely  correct  results  that  chemical  analysis  is  likely  to  throw 
light  on  the  peculiar  properties  of  those  soils  which,  while  they 
possess  much  general  similarity  in  composition  and  physical  pro- 
perties, are  yet  found  in  practice  to  possess  very  different  agri- 
cultural capabilities.  Many  such  cases  occur  in  every  country, 
and  they  present  the  kind  of  difficulties  in  regard  to  which 
agriculture  has  a  right  to  say  to  chemistry — "These  are  mat- 
ters which  I  hope  and  expect  you  will  satisfactorily  clear  up." 
But  while  agriculture  has  a  right  to  use  such  language,  she  has 
herself  preliminary  duties  to  perform.  She  has  no  right  in  one 
breath  to  deny  the  value  of  chemical  theory  to  agricultural 
practice,  and  in  another  to  ask  the  sacrifice  of  time  and  labor 
in  doing  her  chemical  work.  Chemistry  is  a  wide  field,  and 
many  zealous  lives  are  now  being  spent  in  the  prosecution  of  it^ 
without  at  all  entering  upon  the  domain  of  practical  agriculture. 
It  may  be  that  here  and  there  it  may  fall  in  with  the  humor  or 
natural  bias  of  some  one  chemist  to  apply  his  knowledge  to  this 
most  important  art;  but  hitherto  the  appreciation  of  such  cfforti 


124  CLAY  AND  SAND  IN   SOILS. 

has,  except  by  a  limited  few,  been  so  small — the  reception  of 
scientific  results  and  suggestions  by  the  agricultural  body  gene- 
rally so  ungracious — that  little  wonder  can  exist  that  so  many 
chemists  have  quitted  the  field  in  disgust — that  the  majority  of 
capable  men  should  studiously  avoid  it. 

SECTION   III. COMPARATIVE   COMPOSITION   OF   FERTILE   AND 

BARREN   SOILS. 

With  the  view  of  illustrating  the  deductions  which,  as  above 
stated,  may  be  drawn  from  an  accurate  chemical  analysis,  I 
shall  exhibit  the  composition  of  three  difi'erent  soils,  as  deter- 
mined by  Sprengel,  a  German  agricultural  chemist. 

No.  1  is  a  very  fertile  alluvial  soil  from  East  Friesland,  for- 
merly overflowed  by  the  sea,  but  for  sixty  years  cultivated  with 
corn  and  pulse  crops,  without  manure. 

No.  2  is  a  fertile  soil  near  Gottingen,  which  produces  excel- 
lent crops  of  clover,  pulse,  rape,  potatoes,  and  tm'nips,  the  two 
last  more  especially  when  vianured  with  gypsum. 

No.  3  is  a  very  barren  soil  from  Luneberg. 

When  washed  with  water  in  the  manner  described  in  page 
76,  they  give  respectively,  from  1000  parts  of  soil — 

No.  1.  No,  2.  No.  3. 

Soluble  saline  matter,           .         .        18  1  1 

Fine  clay  and  organic  matter,       .      937  839  599 

Silicious  sand,      ....        45  160  400 

1000     1000      1000 

The  most  striking  distinction  presented  by  these  numbers  is 
the  large  quantity  of  saline  matter  in  No.  1.  This  soluble  mat- 
ter consisted  of  common  salt,  chloride  of  potassium,  sulphate  of 
potash,  and  sulphate  of  lime,  (gypsum,)  with  traces  of  sulphate 
of  magnesia,  sulphate  of  iron,  and  phosphate  of  soda.  The 
presence  of  this  comparatively  large  quantity  of  these  difi'erent 
Balinc  substances — originally  derived,  no  doubt,  in  great  part 


COMPOSITION   OP   CERTAIN    SOILS    BY   ANALYSIS. 


125 


from  the  sea — was  probably  one  reason  why  it  could  be  so  long 
cropped  without  manure. 

The  unfruitful  soil  is  much  the  lightest  (in  the  agricultural 
sense)  of  the  three,  containing  40  per  cent  of  sand;  but  this  is 
not  enough  to  account  for  its  barrenness,  many  light  soils  con- 
taining a  larger  proportion  of  sand,  and  yet  being  sufficiently 
fertile. 

The  finer  portions,  separated  from  the  sand  and  soluble  mat- 
ter, consisted,  in  1000  parts,  of — 


Organic  matter, 

Silica, 

Alumina,    . 

Lime, 

Magnesia,  . 

Oxide  of  iron,    . 

Oxide  of  manganese. 

Potash, 

Soda, 

Ammonia, 

Chlorine,    . 

Sulphuric  acid,  . 

Pliosphoric  acid. 

Carbonic  acid,     . 

Loss,  . 


No.  L 

No.  2. 

No.  3. 

97 

50 

40 

648 

833 

778 

57 

51 

91 

59 

18 

4 

H 

8 

1 

61 

30 

81 

1 

3 

i 

2 

trace. 

trace. 

4 

do. 

do. 

trace. 

do. 

do. 

2 

do. 

do. 

2 

i 

do. 

4i 

11 

do. 

40 

4i 

do. 

14 

— 

4i 

1000 


1000 


1000 


1.  The  composition  of  No.  1  illustrates  the  first  of  the  general 
deductions  stated  in  the  preceding  section — that  a  considerable 
supply,  namely,  of  all  the  species  of  inorganic  food  is  necessary 
to  render  a  soil  eminently  fertile.  Not  only  does  this  soil  contain 
a  comparatively  large  quantity  of  soluble  saline  matter,  but  it 
contains  also  nearly  10  per  cent  of  organic  matter,  and  what, 
in  connection  with  this,  is  of  great  importance,  nearly  6  per 
cent  of  lime.  The  potash  and  soda,  and  the  several  acids,  are 
also  present  m  sufficient  abundance. 

2.  In  the  second — a  fertile  soil,  but  one  which  cannot  dispeiise 
viith  manure — there  is  little  soluble  saline  matter,  and  in  the 
insoluble  portion  we  see  that  there  are  mere  traces  only  of 


126  PRACTICAI,   DEDUCTIONS. 

potash,  soda,  and  the  important  acids.  It  contains  also  only  5 
per  cent  of  organic  matter,  and  less  than  2  per  cent  of  lime; 
wliich  smaller  proportions,  together  with  the  deficiencies  above 
stated,  remove  this  soil  from  the  most  naturally  fertile  class  to 
that  class  which  is  susceptible,  in  hands  of  ordinary  skill,  of 
being  brought  to,  and  ke;pt  in,  a  very  productive  condition. 

3.  In  the  fine  part  of  the  third  soil,  we  observe  that  there 
are  many  more  substances  deficient  than  in  No.  2.  The  organic 
matter  amounts  apparently  to  4  per  cent,  and  there  seems  to  be 
nearly  half  a  per  cent  of  lime.  But  it  will  be  recollected  that 
this  soil  contains  40  per  cent  of  sand,  (p.  125;)  or  that  in  every 
hundred  of  soil  there  are  only  60  of  the  fine  matter,  of  which 
the  composition  is  presented  in  the  table; — or  100  lb.  of  the 
native  soil  contain  only  2^  lb.  of  organic  matter  and  J  lb.  of 
lime. 

But  all  these  wants  would  not  alone  condemn  the  soil  to 
hopeless  barrenness,  because,  in  favorable  circumstances,  they 
might  all  be  supplied  by  art.  But  the  oxide  of  iron  amounts  to 
8  per  cent  of  this  fine  part  of  the  soil;  a  proportion  of  this  sub- 
stance which,  in  a  soil  containing  so  little  lime  and  organic  mat- 
ter, appears,  from  practical  experience,  to  be  incompatible  with 
the  healthy  growth  of  cultivated  crops.  This  soil,  therefore, 
requires,  not  only  those  substances  of  which  it  is  destitute,  but 
such  other  substances  also,  or  such  a  form  of  treatment,  as  shall 
prevent  the  injurious  effects  of  the  large  portion  of  oxide  of  iron 
it  contains. 

In  these  three  soils,  therefore,  we  have  examples,  first,  of  one 
which  contains  within  itself  all  the  elements  of  fertility ;  second, 
of  a  soil  which  is  destitute,  or  nearly  so,  of  certain  substances 
required  by  plants,  which,  however,  can  be  readily  added  by  the 
ordinary  manures  in  general  use,  and  to  wliich  the  elements  of 
gypsum  are  especially  useful,  in  aiding  it  to  feed  the  potato  and 
the  turnip;  and  third,  of  a  soil  not  only  poor  in  many  of  the 
necessary  species  of  the  inorganic  food  of  plants,  but  too  rich 


THE    BLACK    EARTH    OF   RUSSIA.  121 

in  one  (oxide  of  iron)  which,  when  present  in  excess,  is  usually 
prejudicial  to  vegetable  life. 

This  illustration,  therefore,  will  aid  the  general  reader  in 
comprehending  how  far  rigid  chemical  analysis  is  fitted  to 
throw  light  upon  the  capabilities  of  soils,  and  to  direct  agricul- 
tural practice. 

SECTION    IV. IMPORTANCE    OF    CERTAIN    FORMS    AND    QUANTITIES    OP 

ORGANIC    MATTER   TO    THE     FERTILITY    OF    A    SOIL. 

The,  Mack  earth  of  Russia. — The  Tchornoi  Zem,  or  black  earth 
of  Central  Russia,  illustrates,  in  a  very  striking  manner,  the 
fact,  that  the  kind  and  quantity  of  the  organic  matter  which  a 
soil  contains  are  scarcely  less  influential  upon  its  fertility  than 
the  mineral  constituents  to  which,  in  the  last  section,  I  prin- 
cipally adverted.  This  remarkable  black  soil,  "the  finest  in 
Russia,  whether  for  the  production  of  wheat  or  grass,"  covers 
an  area  of  upwards  of  60,000  square  geographical  miles,  and  is 
said  to  be  everywhere  of  extreme  and  of  nearly  uniform  fer- 
tility. It  nourishes  a  population  of  more  than  twenty  millions 
of  souls,  and  yet  annually  exports  upwards  of  fifty  millions  of 
bushels  of  corn.  This  black  earth  stretches  into  Hungary,  and 
forms  the  largest  extent  of  fertile  soil  possessing  common  and 
uniform  qualities  which  is  anywhere  known  to  exist.  Its  origin 
and  chemical  composition,  therefore,  have  naturally  engaged 
the  attention  both  of  scientific  and  of  practical  observers. 

Its  depth  varies  from  1  or  2  to  20  feet  ;  when  moist,  it  is 
jet  black,  and  when  dry,  of  a  dark  brown.  This  dark  color, 
from  which  it  derives  its  name,  is  due  to  the  presence  of  or- 
ganic, chiefly  vegetable  matter,  in  a  peculiar  decomposed  state, 
minutely  divided  and  intimately  mixed  with  mineral  matter. 
Of  the  weight  of  the  dry  soil,  it  forms,  in  different  samples, 
from  G  to  18  per  cent.  This  vegetable  matter  is  distinguished 
by  two  circumstances. 

1.  That  it  is  in  an  exceedingly  minute  state  of  division,  and 


128  ANALYSIS   OF  THE   BLACK    EARTH, 

is  intimately  mixed  with  finely-divided  mineral  matter.  The 
black  earth,  therefore,  forms  a  comparatively  free  and  open 
soil,  into  which  the  air  penetrates  and  the  roots  of  plants 
descend  freely. 

2.  It  contains  in  a  state  of  combination  a  considerable  pro- 
portion of  nitrogen.  In  different  samples  this  constituent  has 
been  found  to  vary  from  2|  (Payen)  to  eight  per  cent  (Schmidt) 
of  the  weight  of  the  organic  matter.  Through  the  action  of 
the  air,  this  nitrogen  will  favor  the  production  in  the  soil  of 
nitric  acid,  ammonia,  and  other  soluble  compounds  containing 
nitrogen,  which  I  have  already  described  as  propitious  to  the 
growth  of  plants. 

But  in  this  black  earth  the  composition  of  the  mineral  or 
inorganic  part  is  also  such  as  to  promote  fertility.  In  one 
of  the  richest  varieties,  in  which  the  organic  matter  amounted 
to  18  per  cent,  the  mineral  matter  was  found  to  consist  of — 


Per  cent. 

Potaah, 

5.81 

Soda,              

2.31 

Lime,              

2.60 

Magnesia, 

0.95 

Alumina  and  oxide  of  iron,  with  traces  of 

pliosphoric  acid,     .     .      ,  . 

17.32 

Silica,  of  wliicli  7  or  8  per  cent  were  soluble. 

70.94 

99.93 

"We  see  in  this  analysis  an  abundant  supply  of  those  mineral 
substances  which  appear  to  be  so  necessary  to  the  healthy 
growth  of  plants. 

The  general  results  of  our  analytical  examination  of  soils, 
therefore,  are  chiefly  these — 

a.  That  a  due  admixture  of  organic  matter  is  favorable  to 
the  fertility  of  a  soil. 

h.  That  this  organic  matter  will  prove  the  more  valuable  in 
proportion  to  the  quantity  of  nitrogen  it  holds  in  combination. 

c.  That  the  mineral  part  of  the  soil  must  contain  all  thost 
substances  which  are  met  with  in  the  ash  of  the  plant,  and  in 


AND   CAUSES   OP   ITS   FEKTILITT.  129 

such  a  state  of  chemical  combination  that  the  roots  of  plants 
can  readily  take  them  up  in  the  requisite  proportion. 

It  is  to  the  long  accumulation  of  the  remains  of  forests,  or 
other  abundant  ancient  vegetation,  that  the  color  of  the  Black 
earth,  and  its  richness  in  organic  matter,  is,  with  the  greatest 
probability,  ascribed. 

SECTION  V. —  OF  THE  DIRECT  REL.iTION  THAT  EXISTS  BETWEEN  THE 
CHARACTER  OF  THE  SOIL  AND  THE  KIND  OF  PLANTS  THAT  NATU- 
RALLY GROW  UPON  IT. 

The  importance  of  a  minute  study  of  the  chemical  composi- 
tion of  soils  will,  perhaps,  be  most  readily  appreciated  by  a 
glance  at  the  very  different  kinds  of  vegetables  which,  under 
the  same  circumstances,  different  soils  naturally  produce  ;  in 
other  words,  by  a  glance  at  their  botanical  relations. 

There  are  none  so  little  skilled  in  regard  to  the  capabilities  of 
the  soil,  as  not  to  be  aware  that  some  lands  naturally  produce 
abundant  herbage  or  rich  crops,  while  others  refuse  to  yield  a 
nourishing  pasture,  and  are  deaf  to  the  often-repeated  solicita- 
tions of  the  diligent  husbandman.  There  exists,  therefore,  a 
universally  understood  connection  between  the  kind  of  soil  and 
the  kind  of  plants  that  naturally  grow  upon  it.  It  is  interest- 
ing to  observe  how  close  this  relation  in  many  cases  is. 

1.  The  sands  of  the  sea-shore,  the  margins  of  salt  lakes  and 
the  surfaces  of  salt  plains,  like  the  Russian  steppes,  are  distin- 
guished by  their  peculiar  tribes  of  salt-loving  plants — by  varie- 
ties of  salsola,  salicornia,  &c.  The  Triticum  junceum  (sea 
wheat)  grows  on  the  seaward  slopes  of  the  downs  at  no  great 
distance  from  the  sea.  The  drifted  sands  more  removed  from 
the  beach  produce  their  own  long,  waving,  coarser  grass, — the 
Arundo  arenaria,  (sea  bent,)  the  Elymus  arenarius,  (sea  lime 
grass,)  and  the  Car  ex  araiarius,  (sand  sedge,)  the  roots  of 
which  plants  bind  the  shifting  sands  together.  The  beautiful 
6* 


130  PLANTS  SELECT  THE  SOILS 

sea  pink  spreads  itself  over  the  loose  downs — ^while  further 
inland,  and  as  the  soil  changes,  new  vegetable  races  appear, 

2.  The  peaty  hills  and  flats  of  our  island  naturally  clothe 
themselves  with  the  common  ling,  {Calhina  vulgaris,)  the  fine- 
leaved  heath,  {Erica  cincrea,)  and  with  the  cross-leaved  heath, 
{Erica  tetraliz.)  When  drained  and  laid  down  to  grass,  or 
when  they  exist  as  natural  meadows,  they  produce  one  soft 
woolly  grass  almost  exclusively — the  Holctcs  lanatus.  After 
they  are  limed,  these  same  soils  become  propitious  to  green 
crops  and  produce  much  straw,  but  refuse  to  fill  the  ear.  The 
grain  is  thick-skinned,  and  therefore  light  in  flour.  There  is  a 
greater  tendency  to  produce  cellular  fibre,  and  the  insoluble 
matter  associated  with  it,  than  the  more  useful  substances  starch 
and  gluten. 

3.  On  the  margins  of  water-courses  in  which  silica  abounds, 
the  mare's  tail  {Equisetum)  springs  up  in  abundance  ;  while,  if 
the  stream  contain  much  carbonate  of  lime,  the  water-cress 
appears  and  lines  the  sides  and  bottom  of  its  shallow  bed,  some- 
times for  many  miles  from  its  source. 

4.  The  Cornish  heath  (Erica  vagans)  shows  itself  rarely 
above  any  other  than  the  serpentine  rocks  ;  the  red  broom- 
rape,  (Orobanche  rubra,)  only  on  trap  or  basaltic  rocks  ;  the 
Atiemone  Pulsatilla  on  the  dry  banks  of  chalky  mounds,  as  in 
the  neighborhood  of  Newmarket  ;  the  lady's  slipper  on  calca- 
reous formations  only  ;  the  Medicago  lupulina  on  soils  which 
abound  in  marl ;  while  the  red  clover  and  the  vetch  delight  in 
the  presence  of  gypsum,  and  the  white  clover  in  that  of  alka- 
?ine  matter  in  the  soil. 

So  the  red  and  white  fire-weeds,  Epilobium  colaratum,  and 
Erichtites  hierecifolitis,  cover  with  their  bright  blossoms  every 
open  space  in  the  North  American  woods,  over  which  the  fires, 
so  frequent  there,  have  run  during  the  previous  year.  The 
ashes  of  the  burned  trees  and  underwood  are  specially  grateful 
to  the  seeds  of  these  plants,  which  in  vast  quantities  lie  dor- 
mant in  the  soils, 


ON    WHICH    THEY    PREFER   TO    GROW.  131 

6.  The  clays,  too,  have  their  likings.  The  Rest  harrow, 
(Ononis  arvensis,)  delights  in  the  weald,  the  gault,  and  the 
plastic  clays,  but  passes  by  the  green-sand  and  chalk  soils,  by 
which  these  clays  are  separated  from  each  other.  The  oak,  in 
like  manner,  characterises  the  clays  of  the  weald  ;  while  the 
elm  flourishes,  in  preference,  on  the  neighboring  soils  of  the 
green-sand  formation. 

6.  Then,  again,  plants  seem  to  alternate  with  each  other  on 
the  same  soil.  Burn  down  a  forest  of  pines  in  Sweden,  and 
one  of  birch  takes  its  place  for  a  while.  The  pines  after  a 
time  again  spring  up,  and  ultimately  supersede  the  birch.  The 
same  takes  place  naturally.  On  the  shores  of  the  Rhine  are 
seen  ancient  forests  of  oak  from  two  to  four  centuries  old,  gra- 
dually giving  place  at  present  to  a  natural  growth  of  beech, 
and  others  where  the  pine  is  succeeding  to  both.  In  the  Pala- 
tinate, the  ancient  oak-woods  are  followed  by  natural  pines; 
and  in  the  Jura,  the  Tyrol,  and  Bohemia,  the  pine  alternates 
with  the  beech. 

These  and  other  similar  differences  are  believed  to  depend  in 
great  part  upon  the  chemical  composition  of  the  soil.  The  slug 
may  live  well  upon,  and  therefore  infest,  a  field  almost  deficient 
in  lime  ;  the  common  land  snail  will  abound  at  the  roots  of  the 
hedges  only  where  lime  is  plentiful,  and  can  easily  be  obtained 
for  the  construction  of  its  shell.  So  it  is  with  plants.  Each 
grows  spontaneously  where  its  wants  can  be  most  fully  and 
most  easily  supplied.  If  they  cannot  move  from  place  to  place 
like  the  living  animal,  yet  their  seeds  can  lie  dormant,  until 
either  the  hand  of  man  or  the  operation  of  natural  causes  pro- 
duces such  a  change  in  their  position,  in  reference  to  light, 
heat,  &c.,  as  to  give  them  an  opportunity  of  growing — or  in 
the  composition  and  physical  qualities  of  the  soil  itself,  as  to  fit 
it  for  ministering  to  their  most  important  wants. 

And  such  changes  do  naturally  come  over  the  soil.  The  oak, 
after  thriving  ior  long  generations  on  a  particular  spot,  gradu- 
ally sickens;  its  entire  race  dies  out,  and  other  races  succeed  it 


18S  PLANTS    SICKEN    ON    SOMB,    SOILS. 

Has  the  operation  of  natural  causes  gradually  removed  from 
the  soil  that  which  favored  the  oak,  and  introduced  or  given 
the  predominance  to  those  substances  which  favor  the  beech  or 
the  pine  ?  On  the  light  soils  of  the  state  of  Kew  Jersey  the 
peach  tree  used  to  thrive  better  than  anything  else,  and  large 
suras  of  money  were  made  from  the  peach  grounds  in  that 
state.  But  of  late  years  they  have  almost  entirely  failed.  In 
Scotland,  the  Scotch  fir  has  been  known  at  once  to  die  out  over 
an  area  of  500  or  600  acres — and  the  forests  of  larch  are  now 
in  many  localities  exhibiting  a  similar  decay.  This  decay  is 
often,  I  believe,  owing  to  the  presence  of  noxious  matters  in 
the  subsoil,  but  it  is  due  in  some  cases  also  to  a  natural  change 
in  the  composition  and  character  of  the  several  soils,  which  has 
taken  place  since  the  peach,  the  fir,  and  the  larch  trees  were 
first  planted  upon  them. 

In  the  hands  of  the  farmer,  the  land  grows  sick  of  this  crop 
— ^it  becomes  tired  of  that.  These  facts  may  be  regarded  as 
indications  of  a  change  in  the  chemical  composition  of  the  soil. 
This  alteration  may  proceed  slowly  and  for  many  years;  and 
the  same  crops  may  still  grow  upon  it  for  a  succession  of  rota- 
tions. But  at  length  the  change  is  too  great  for  the  plant  to 
bear;  it  sickens,  yields  an  unhealthy  crop,  and  ultunately  refuses 
altogether  to  grow. 

The  plants  we  raise  for  food  have  similar  likes  and  dislikes 
with  those  that  are  naturally  produced.  On  some  kinds  of  food 
they  thrive ;  fed  with  others,  they  sicken  or  die.  The  soil  must 
therefore  be  prepared  for  their  special  growth. 

In  an  artificial  rotation  of  crops  we  only  follow  nature.  One 
kind  of  crop  extracts  from  the  soil  a  certain  quantity  of  all  the 
inorganic  constituents  of  plants,  but  some  of  these  in  much 
larger  proportions  than  others.  A  second  kind  of  crop  carries 
off",  in  preference,  a  large  quantity  of  those  substances  of  which 
the  former  had  taken  little ;  and  thus  it  is  clearly  seen,  both 
why  an  abundant  manuring  may  so  alter  the  composition  of  the 
loil  as  to  enable  it  to  grow  almost  any  crop;  and  why,  at  Uie 


AGRICULTURE   A   CHEMICAL   ART.  133 

same  time,  this  soil  may,  in  succession,  yield  more  abundant 
crops,  and  in  greater  number,  if  the  kind  of  plants  sown  and 
reaped  be  so  varied  as  to  extract  from  the  soil,  one  after  the 
other,  the  several  different  substances  vi^hich  the  manure  we 
have  originally  added  is  known  to  contain. 

So  with  regard  to  the  organic  matter  which  soils  contain. 
That  form  of  organic  food  which  suits  one,  may  not  equally  favor 
another  species  of  plant,  and  thus,  at  different  times,  different 
species  may  be  most  suited  to  the  chemical  condition  of  tho 
same  field. 

The  management  and  tilling  of  the  soil,  in  fact,  is  a  branch 
of  practical  chemistry  which,  like  the  art  of  dyeing,  of  lead- 
smelting,  or  of  glass-making,  may  advance  to  a  certain  degree 
of  perfection  without  the  aid  of  pure  science,  but  which  can 
only  have  its  processes  explained,  and  be  led  on  to  shorter,  more 
simple,  more  economical,  and  more  perfect  processes,  by  the 
aid  of  scientific  principles. 


CHAPTER  X. 

Of  the  general  improvement  of  the  soil,  and  how  the  pradent  man  will 
commence  such  improvement. — Mechanical  methods  of  improving  the 
soil. — Draining,  cause  of  the  benefits  produced  by  it. — Draining  of  appa- 
rently dry  land. — Summary  of  the  economical  advantages  of  draining.— 
Depth  to  which  drains  ouglit  to  be  dug. — Effects  produced  by  the  rains 
as  they  descend  through  the  soil. 

The  soil,  in  its  natural  condition,  is  possessed  of  certain  ex- 
isting and  obvious  qualities,  and  of  certain  other  dormant  capa- 
bilities. How  are  the  existing  qualities  to  be  improved, — the 
dormant  capabilities  to  be  awakened  ? 

SECTION  I. — OF  THE  GENERAL  IMPROVEMENT  OF  THE  SOIL,  AND  HOW 
THE  PRUDENT  MAN  WILL  COMMENCE  SUCH  IMPROVEMENT. 

There  are  few  soils  to  which  something  may  not  still  be  done 
in  the  way  of  improvement,  while  by  far  the  greatest  breadth 
of  the  land,  in  almost  every  country,  is  still  susceptible  of  ex- 
tensive amelioration.  In  its  present  condition,  the  art  of  culti- 
vating the  land  in  England  generally,  differs  from  nearly  all 
other  arts  practised  among  us  in  this — that  he  who  undertakes 
it  later  in  life,  who  brings  to  it  a  mind  already  matured,  a  good 
ordinary  education,  a  sound  judgment,  and  a  fair  share  of  pru- 
dence, who  turns  to  it  as  a  new  pursuit,  is  often  seen  to  take 
the  lead  among  the  agriculturists  of  the  district  in  which  he 
settles.  He  comes  to  the  occupation  free  from  the  trammels  of 
old  customs,  old  methods,  and  old  prejudices,  and  hence,  is  free 
to  adopt  a  sounder  practice  and  more  rational  methods  of  cul- 
tivation. Such  men,  from  lack  of  prudence  or  other  causes, 
have  not  always  pro°pered  in  their  worldly  affairs,  but  they 


GENERAL   IMPROVEMENT   OF    SOILS,  135 

have  in  very  many  districts  been  the  beginners  of  agricultural 
improvements,  the  introducers  of  better  systems  of  culture,  and 
consequently  public  benefactors  to  the  country. 

What  ought  to  be  the  course  of  such  a  man  in  embarking 
any  serious  amount  of  capital  in  this  new  pursuit  ?  What  that 
of  an  intelligent  practical  farmer  on  establishing  himself  in  a 
new  district  ? 

Suppose  them  to  be  equally  well  read  in  the  theory  and  in 
the  general  practice  of  agriculture,  they  will — 

1.  Examine  the  quality  of  the  land,  its  soil  and  its  subsoil, 
the  exposure  and  the  climate,  the  access  to  markets  and  to  ma- 
nures ;  and  generally,  they  will  inquire  what,  in  that  district, 
are  the  more  common  sources  of  disappointment  to  the  indus- 
trious farmqr. 

2.  Consider  what,  in  the  abstract,  theory  would  indicate  as 
the  most  proper  treatment  for  such  land  so  situated,  and  the 
amount  of  produce  it  ought  to  yield. 

3.  Inquire  what  is  the  actual  produce  of  the  land,  what  the 
actual  practice  in  the  district,  and  especially  the  cause  or  rea- 
son of  any  local  peculiarities  in  the  practice  which  may  be 
found  to  prevail.  There  are  often  good  reasons  for  local  pecu- 
liarities which  new  settlers  injure  themselves  by  overlooking, 
and  find  out  too  late  for  their  own  interest.  The  prudent  man 
may  look  with  suspicion  upon  such  local  customs,  but  he  will 
be  satisfied  that  there  is  no  sufficient  reason  for  their  adoption, 
before  he  finally  reject  them  to  follow  the  indications  of  theory 
alone. 

In  illustration  of  this  I  may  mention,  that  a  friend  of  mine 
in  Ayrshire,  in  agreeing  to  become  the  tenant  of  a  farm  which 
appeared  to  have  been  exhausted  by  the  previous  occupant, 
founded  his  hopes  of  success  on  ploughing  deeper,  and  thus 
bringing  a  new  soil  to  the  surface,  and  his  anticipations  have 
not  been  disappointed  by  the  result.  On  the  other  hand,  I 
know  of  an  instance  in  Berkshire,  where,  under  the  direction  of 
a  new  agent,  deeper  ploughing  was  introduced,  and  the  crops 


tS%  IMPROVEMEKT    BY    DRAINING. 

proved  in  consequence  almost  an  entire  failure.  In  this  case 
sound  theory  indicated  a  deeper  ploughing,  but  local  experience 
had  proved  that  shallow  ploughing  alone  could  preserve  the 
crops  from  the  fatal  ravages  of  insect  tribes.  The  local  custom 
here,  therefore,  was  founded  upon  a  good  reason,  one  sufficient 
to  deter  the  prudent  man  from  hasty  or  extensive  experiments, 
though  not  enough  to  prevent  him  from  seeking  out  some  method 
of  so  extirpating  the  insect  destroyers  from  his  land,  as  to  enable 
him  afterwards  to  avail  himself  of  its  greater  depth  of  soil. 

Suppose  it  now  to  be  determined  that  the  laad  is  capable  of 
being  made  to  yield  a  larger  produce,  the  questions  recur — what 
is  the  kind  of  improvement  for  which  this  land  will  give  the 
best  return  ?  how  is  this  improvement  to  be  best;  most  fully, 
and  at  the  same  time  most  economically  brought  about  ? 

All  soils  may  be  arranged  into  one  or  other  of  two  classes. 

1.  Those  which,  like  No.  1,  (p.  125)  contain  in  themselves 
an  abundant  supply  of  all  those  things  which  plants  require, 
and  are  therefore  fitted  chemically  to  grow  any  crop. 

2.  Those  which,  like  Nos.  2  and  3,  (p.  126)  are  deficient  in 
some  of  those  substances  on  which  plants  live,  and  are  thei;e- 
fore  not  fitted  to  grow,  perhaps,  any  one  crop  with  luxuriance. 

Both  of  these  classes  of  soils,  as  they  are  naturally  met  with, 
are  susceptible  of  improvement,  the  former  by  mechanical 
methods  chiefly,  the  latter  by  mechanical  partly,  but  chiefly  by 
chemical  methods.  In  the  present  chapter  we  shall  consider  the 
mechanical  methods  of  improving  the  soil. 

SECTION  II. OF  IMPROVING  THE  SOIL  BY  DRAINING,  AND  THE  CAUSES 

OP  THE  BENEFITS  PRODUCED  BY  IT. 

The  first  step  to  be  taken  in  order  to  increase  the  fertility  of 
nearly  all  the  improvable  lands  of  Great  Britain,  is  to  drain 
them.     The  advantages  that  result  from  draining  are  manifold. 

1°.  The  presence  of  too  much  water  in  the  soil  keeps  it  cou- 
Btantly  cold.    The  heat  of  the  sun's  rays,  which  is  intended  by 


fiFFECTS   OP   DRAINING.  137 

nature  to  wa»  m  the  land,  is  expended  in  evaporating  the  water 
from  its  surface  ;  and  thus  the  plants  never  experience  that 
genial  warmth  about  their  roots  which  so  much  favors  their 
rapid  growth. 

The  temperature  which  a  dry  soil  will  attain  in  the  summer 
time  is  often  very  great.  Sir  John  Herschel  observed,  that  at 
the  Cape  of  Good  Hope  the  soil  attained  a  temperature  of  150" 
Fahrenheit,  when  that  of  the  air  was  only  120°  ;  and  Hum- 
boldt says,  that  the  warmth  of  th-e  soil  between  the  tropics 
often  rises  to  from  124°  to  136°,  (see  p.  119.) 

When  the  land  is  full  of  water,  it  is  only  after  long  droughts, 
and  when  it  has  been  thoroughly  baked  by  the  sun,  that  it  be- 
gins to  attain  the  temperature  which  dry  land  under  the  same 
sun  may  have  reached,  day  after  day,  probably  for  weeks  before. 

2'^.  Where  too  much  water  is  present  in  the  soil,  also,  that 
portion  of  the  food  of  the  plant  which  the  soil  supplies  is  so 
much  diluted,  that  either  a  much  greater  quantity  of  fluid 
must  be  taken  in  by  the  roots — much -more  work  done  by  them, 
that  is — or  the  plant  will  be  scantily  nourished.  The  presence 
of  so  much  water  in  the  stem  and  leaves  keeps  down  their  tem- 
perature also,  when  the  sunshine  appears — an  increased  evapo- 
ration takes  place  from  their  surfaces — a  lower  natural  heat,  in 
consequence,  prevails  in  the  interior  of  the  plant,  and  the 
chemical  changes,  on  which  its  growth  depends,  proceed  with 
less  rapidity. 

3°.  By  the  removal  of  the  water,  the  physical  properties  of 
the  soil,  also,  are  in  a  remarkable  degree  improved.  Dry  pipe- 
clay can  be  easily  reduced  to  a  fine  powder,  but  it  naturally, 
and  of  its  own  accord,  runs  together  when  water  is  poured 
upon  it.  So  it  is  with  clays  in  the  field.  When  wet,  they  are 
close,  compact,  and  adhesive,  and  exclude  the  air  from  the 
roots  of  the  growing  plant.  But  remove  the  water  and  they 
gradually  contract,  crack  in  every  direction,  become  thus  open, 
triable,  and  mellow,  more  easily  and  cheaply  worked,  and  per- 
vious to  the  air  in  every  direction. 


1B$  DRAIKING   OF  LIGHT  SOILS. 

4"^.  The  access  of  this  air  is  essential  to  the  fertility  of  the 
soil,  and  to  the  healtliy  growth  of  most  of  our  cnltivated 
crops.  The  insertion  of  drains  not  only  makes  room  for  the 
air  to  enter  by  removing  the  water,  but  actually  compels  the 
air  to  penetrate  into  the  under  parts  of  the  soil,  and  renews  it 
at  every  successive  fall  of  rain.  Open  such  outlets  for  the 
water  below,  and  as  this  water  sinks  and  trickles  away,  it  will 
suck  the  air  after  it,  and  draw  it  into  the  pores  of  the  soil 
wherever  itself  has  been. 

Vegetable  matter  becomes  of  double  value  in  a  soil  thus 
dried  and  filled  with  atmospheric  air.  When  drenched  with 
water,  this  vegetable  matter  either  decomposes  very  slowly,  or 
produces  acid  compounds  more  or  less  unwholesome  to  the 
plant,  and  even  exerts  injurious  chemical  reactions  upon  the 
earthy  and  saline  constituents  of  the  soil.  In  the  presence  of 
air,  on  the  contrary,  this  vegetable  matter  decomposes  rapidly, 
produces  carbonic  acid  in  large  quantity,  as  well  as  other  com- 
pounds on  which  the  plant  can  live,  and  even  renders  the  inor- 
ganic constituents  of  the  soil  more  fitted  to  enter  the  roots, 
and  thus  to  supply  more  rapidly  what  the  several  parts  of  the 
plant  require.  Hence,  on  dry  land,  manures  containing  organic 
matter,  (farmyard  manure,  &c.,)  go  farther  or  are  more  profit- 
able to  the  farmer. 

5°.  Nor  is  it  only  stifif  and  clayey  soils  to  which  draining 
can  with  advantage  be  applied.  It  will  be  obvious  to  every 
one,  that  when  springs  rise  to  the  surface  in  sandy  soils,  a 
drain  must  be  made  to  carry  ofi"  the  water  ;  it  will  also  readily 
occur,  that  where  a  sandy  soil  rests  upon  a  hard  or  clayey 
bottom,  drains  may  likewise  be  necessary  ;  but  it  is  not  un- 
frequently  supposed,  that  where  the  subsoil  is  sand  or  gravel, 
thorough  draining  can  seldom  be  required. 

Every  one,  however,  is  familiar  with  the  fact,  that  when 
water  is  applied  to  the  bottom  of  a  flower-pot  full  of  soil,  it 
will  gradually  find  its  way  towards  the  surface,  however  light 
the  soil  may  be.    So  it  is  in  sandy  soils  or  subsoils  in  the  open 


SOIL   LIABLE  TO   BE   BURNGD   UP.  139 

field — all  possess  a  certain  power  of  sucking  up  water  from 

beneath,   (p.  118.)     If  water  abound  at  the  depth  of  a  few 

feet,  or  if  it  so  abound  at  certain  seasons  of  the  year,  that 

water  will  rise  towards  tlie  surface  ;   and  as  the  sun's  heat 

dries  it  off  by  evaporation,  more  water  will  follow  to  supply  its 

place.     This  attraction  from  beneath  will  always  go  on  when 

the  air  is  dry  and  warm,  and  thus  a  double  evil  will  ensue — 

the  soil  will  be  kept  moist  and  cold,  and  instead  of  a  constant 

circulation  of  air  downwards,  there  will  be  a  constant  current 

of  water  upicards.     Thus  will  the  roots,   the  under  soil,  and 

the  organic  matter  it  contains,  be  all  deprived  of  the  benefits 

which  the  access  of  the  air  is  fitted  to  confer,  and  both  the 

crops  and  the  farmer  will  suffer  in  consequence.*     The  remedy 

for  these  evils  is  to  be  found  in  an  efficient  system  of  drainage. 

6°.  It  is  a  curious  and  apparently  a  paradoxical  observation, 

that   draining  often   improves  soils   on  which   the  crops   are 

liable  to  be  burned  up  in  seasons  of  drought.     Yet,  upon  a 

little  consideration,  the  fact  becomes  very  intelligible.     Let 

,     a.  5  be  the  surface  of  the  soil,  and  c  d  the 

a 0 

level  at  which  the  water  stagnates,  or  below 

"  which  there  is  no  outlet  by  drains  or  natural 


*  ^  openings.  The  roots  will  readily  penetrate 
to  c  ^;  but  they  will  in  general  refuse  to  descend  farther, 
because  of  the  unwholesome  substances  which  usually  collect 
in  water  that  is  stagnant.  Let  a  dry  season  come,  and,  their 
roots  having  little  depth,  the  plants  will  be  more  or  less  speed- 
ily burnt  up.  And  if  water  ascend  from  beneath  the  line  c  d, 
to  moisten  the  upper  soil,  it  will  bring  with  it  those  noxious 
Substances  into  which  the  roots  have  already  refused  to  pen- 
etrate, and  will  cause  the  crop  to  droop  and  wither.     But  put 

*  A  few  niiles  south  of  the  town  of  Elgin  in  Morayshire,  i  was  shown  a 
tract  of  land  on  which  the  crops  wore  usually  tliree  weeks  later  than  on 
another  tract,  separated  from  it  by  a  small  stream.  Beneath  the  fonjier 
,vas  a  pan  at  the  depth  of  3  feet,  which  prevented  the  surfoce-water 
from  sinking  beyond  that  level,  and  tlius  retarded  the  growth  of  the  crop 


a40  removal  of  ochrey  matter 

in  a  drain,  and  lower  the  level  of  the  water  to  c  /,  and  the 
rains  will  wash  out  the  noxious  water  from  the  subsoil,  and  the 
roots  will  descend  deep  into  it  ;  so  that  if  a  drought  again 
come,  it  may  parch  the  soil  above  c  d,  as  before,  without  in- 
juring the  plan>j,  since  now  they  are  watered  and  fed  by  the 
soil  beneath,  into  which  the  roots  have  descended. 

1°.  In  many  parts  of  the  country,  and  especially  in  the  red- 
sandstoue  districts,  the  oxide  or  rust  of  iron  abounds  so  much 
in  the  soil,  or  in  the  springs  which  ascend  into  it,  as  gradually 
to  collect  in  the  subsoil,  and  form  a  more  or  less  impervious 
layer  or  pan,  into  which  the  roots  cannot  penetrate,  and 
through  which  the  surface-water  refuses  to  pass.  Such  soils 
are  benefited,  for  a  time,  by  breaking  up  the  pan  where  the 
plough  can  reach  it ;  but  the  pan  gradually  forms  again  at  a 
greater  depth,  and  the  evils  again  recur.  In  such  cases,  the 
insertion  of  drains  below  the  level  of  the  pan  is  the  most  cer- 
tain mode  of  permanently  improving  the  soil.  If  the  pan  be 
now  broken  up,  the  rains  sink  through  into  the  drains,  and 
gradually  wash  out  of  the  soil  the  iron  which  would  otherwise 
have  only  sunk  to  a  lower  level,  and  have  again  formed  itself 
into  a  solid  cake. 

8°.  It  is  not  less  common,  even  in  rich  and  fertile  districts, 
to  see  crops  of  beans,  or  oats,  or  barley,  come  up  strong  and 
healthy,  and  shoot  up  even  to  the  time  of  flowering,  and  then 
begin  to  droop  and  wither,  till  at  last  they  more  or  less  com- 
pletely die  away.  So  it  is  rare  in  many  places  to  see  a  second 
year's  clover  crop  come  up  strong  and  healthy.  These  facts 
indicate,  in  general,  the  presence  of  noxious  matters  in  the 
subsoil,  which  are  reached  by  the  roots  at  an  advanced  stage 
of  their  growth,  but  into  which  they  cannot  penetrate  without 
injury  to  the  plant.  The  drain  calls  in  the  aid  of  the  rains  of 
heaven  to  wash  away  these  noxious  substances  from  the  soil, 
and  of  the  air  to  change  their  nature,  and  this  is  the  most 
likely,  as  well  as  the  cheapest,  means  by  which  these  evils  can 
be  prevented. 


AND   OF    SALINE   INCKUSTATIONS.  141 

9°.  Another  evil  in  some  countries  presents  itself  to  the  prac- 
tical farmer.  Saline  substances  are  in  certain  quantity  bene- 
ficial, nay,  even  necessary  to  the  growth  of  plants.  In  excess, 
however,  they  are.  injurious,  and  kill  many  valuable  crops.  1 
have  already  adverted  to  the  existence  of  such  saline  substances 
in  the  soil,  and  to  the  fact  of  their  rising  in  incrustations  to  the 
surface  (p.  T6)  when  droughts  prevail. 

In  some  countries,  as  in  the  plains  of  Athens,  and  near  the 
city  of  Mexico,  they  come  to  the  surface  in  such  quantity  as 
actually  to  kill  the  more  tender  herbage,  and  to  permit  only  the 
stronger  plants  to  grow.  In  the  plains  of  Athens,  wlien  the 
rainy  season  ends,  a  rapid  evaporation  of  water  from  the  surface 
begins.  The  water,  as  it  rises  from  beneath,  brings  much  saline 
matter  with  it.  This  it  leaves  behind  as  it  ascends  in  vapor, 
and  thus  at  length  so  overloads  the  surface-soil  that  tender  grass 
refuses  to  grow,  though  the  stronger  wheat  plant  thrives  well 
and  comes  to  maturity. 

This  result  could  scarcely  happen  if  an  outlet  beneath  were 
provided  for  the  waters  which  fall  during  the  rainy  season. 
These  would  wash  out  and  carry  away  the  excess  of  saline  mat- 
ter which  exists  in  the  under  soil,  and  would  thus,  when  the  dry 
weather  comes,  prevent  it  from  ascending  in  such  quantities  as 
to  injure  the  more  tender*herbage. 

It  may  be  objected  to  this  suggestion,  that  drains  in  such 
countries  would  render  more  dry  a  soil  already  too  much  parched 
by  the  hot  suns  of  summer.  It  is  doubtful,  however,  if  this 
would  really  be  the  case.  Deep  drains,  as  in  the  case  above 
explained,  (6°,)  would  enable  the  roots  to  penetrate  deeper,  and 
would  thus  render  them  more  independent  of  the  moisture  of 
the  surface-soil. 

10°.  On  this  subject  I  shall  add  one  important  practical  re- 
mark, which  will  readily  suggest  itself  to  the  geologist  who  has 
studied  the  action  of  air  and  water  on  the  various  clay-beds 
that  occur  here  and  there,  as  members  of  the  series  of  stratified 
rocks.     The,r&  art  no  tlays  which  do  tint  gradually  soflen  undet 


142  DEPTH   OF  DRAINS. 

th£  united  influence  of  air,  of  frost,  and  of  running  water.  It  is 
false  economy,  therefore,  to  lay  down  tiles  of  the  common  horse-  shoe 
form  without  sole^,  however  hard  and  stiff  the  clay  subsoil  may 
appear  to  be.  In  the  course  of  ten  or  fifteen  years,  the  stiffest 
clays  will  generally  soften  so  much  as  to  allow  the  tile  to  sink  to 
some  extent — and  many  very  much  sooner.  The  passage  for 
the  water  is  thus  gradually  narrowed;  and  when  the  tile  has 
sunk  a  couple  of  inches,  the  whole  may  have  to  be  taken  up. 
Thousands  of  miles  of  drains  have  been  thus  laid  down,  both  in 
the  low  country  of  Scotland  and  in  the  southern  counties  of 
England,  which  have  now  become  nearly  useless.  The  extend- 
ing use  of  the  pipe-tile  will,  it  is  to  be  hoped,  gradually  lessen 
the  chances  of  pecuniary  loss,  which  the  above  practice  involves. 

SECTION   III. — SUMMARY   OF   THE   ECONOMICAL  ADVANTAGES   OF 
DRAINING. 

The  economical  advantages  of  draining  in  such  soils  as  we 
possess  are  chiefly  these  : — 

1.  Stiff  soils  are  more  easily  and  more  cheaply  worked. 

2.  Lime  and  manures  have  more  effect,  and  go  farther. 

3.  Seed- time  and  harvest  are  earlier  and  more  sure. 

4.  Larger  crops  are  reaped,  and  of  better  quality. 

5.  Valuable  crops  of  wheat  and  turnips  are  made  to  grow 
where  scanty  crops  of  oats  were  formerly  the  chief  return. 

6.  Naked  fallows  are  rendered  less  necessary,  and  more  pro- 
fitable rotations  can  be  introduced. 

7.  The  climate  is  improved,  and  rendered  not  only  more  suited 
to  the  growth  of  crops,  but  more  favorable  to  the  health  of  man 
and  other  animals. 

SECTION  IV. OF   THE   DEPTH   TO   WHICH   DRAINS   OUGHT  TO   BE  DUG. 

Much  has  lately  been  written  in  regard  to  the  depth  to  which 
drains  ought  to  be  dug  in  a  system  of  thorough  drainage.    It  is 


ADVANTAGES    OF   DRAINING.  143 

difficult,  perhaps  impossible,  to  establish  any  empirical  or  gene- 
ral rule  upon  tliis  subject;  but  there  are  certain  indisputable 
points  which  will  serve  to  guide  the  intelligent  farmer  in  most 
cases  which  are  likely  to  occur. 

1°.  It  is  acknowledged,  as  a  general  rule,  to  be  of  great  im- 
portance, that  the  soil  should  be  deepened- — that  it  should  be 
opened  up,  for  the  descent  of  the  roots,  to  the  greatest  depth  to 
which  it  can  be  economically  done.  Kow,  by  the  use  of  the  sub- 
soil plough  or  the  fork,  the  soil  can  be  stirred  to  a  depth  of 
from  22  to  24  inches.  The  tile — or  the  top  of  the  drain,  if  made 
of  stones — should  be  at  least  three  inches  clear  of  this  disturb- 
ance of  the  upper  soil ;  and  as  most  tiles  will  occupy  at  least  3 
inches,  we  reach  30  inches  as  the  minimum  depth  of  a  tile  drain, 
and  about  3  feet  as  the  minimum  depth  of  a  stone  drain,  in 
which  the  layer  of  stones  has  a  depth  of  not  more  than  9  inches. 

2°.  Where  the  outfall  is  bad,  and  a  depth  of  30  or  36  inches 
cannot  be  obtained,  the  drains  should  be  made  as  deep  as  they 
can  be  made  to  run  and  deliver  water. 

3°.  The  roots  of  our  corn  and  other  crops  will,  in  favorable 
circumstances,  descend  to  a  depth  of  4  or  5  feet.  They  do  so 
in  quest  of  food,  and  the  crop  above  ground  is  usually  the  more 
luxuriant  the  deeper  the  roots  are  enabled  to  penetrate.  It  is, 
therefore,  theoretically  desirable  to  dry  the  soil  to  a  greater 
depth  even  than  3  feet,  where  it  can  be  done  without  too  great 
an  outlay  of  money. 

4°.  The  question  of  economy,  therefore,  is  one  of  great  im- 
portance in  this  inquiry.  In  some  places  it  costs  as  much  to 
dig  out  the  fourth  or  lowest  foot  as  is  paid  for  the  upper  three ; 
and  this  additional  cost  is,  in  many  localities,  a  valid  reason  for 
limiting  the  depth  to  30  inches,  or  3  feet. 

5°.  But  the  question  of  economy  ought  to  be  disregarded, 
and  deeper  drains  dug  where  springs  occur  beneath,  or  where, 
by  going  a  foot  deeper,  a  bed  or  layer  is  reached  in  which  much 
water  is  present.  The  reason  of  this  is — that  though  water 
may  not  rise  from  this  wet  layer  in  such  quantity  as  actually  to 


144  RAINS  WARM  THS   SOIL. 

run  along  the  drains,  yet  it  may  do  so  in  sufficient  abundance  to 
keep  the  subsoil  moist  and  cold,  and  thus  to  retard  the  develop- 
ment of  the  crops  that  grow  on  its  surface. 

The  above  circumstances  appear  sufficient  to  guide  the  prac- 
tical man  in  most  cases  that  will  present  themselves  to  him.  No 
uniform  depth  can  be  fixed  upon;  it  must  be  modified  by  local 
circumstances. 

In  regard  to  the  distance  apart  at  which  drains  should  be 
placed,  experience  appears  to  be  the  only  satisfactory  guide. 
This  says,  as  yet,  that  18  to  21  feet  are  safe  distances,  and  that 
drains  placed  at  gi'eater  distances  are  doubtful,  and  may  fail  to 
dry  the  land. 

SECTION   V. EFFECTS   PRODUCED   BY  THE   R.VINS    AS  THEY  DESCEND 

THROUGH  THE  SOIL. 

The  most  important  immediate  efiect  of  thorough-drainage 

is,  that  it  enables  the  rain  or  other  surface  water  to  descend 

'  more  deeply  and  escape  more  rapidly  from  the  soil.     It  may  be 

interesting  to  specify  briefly  the  benefits  which  are  known  to 

follow  from  this  descent  of  the  rain  through  the  soil. 

1°.  It  causes  the  air  to  he  renewed. — It  is  believed  that  the 
admission  of  frequently  renewed  supplies  of  air  into  the  soil  is 
favorable  to  its  fertility.  This  the  descent  of  the  rain  pro- 
motes. When  it  falls  upon  the  soil  it  makes  its  way  into  the 
pores  and  fissures,  expelling  of  course  the  air  which  previously 
filled  them.  When  the  rain  ceases,  the  water  runs  off  by  the 
drains  ;  and  as  it  leaves  the  pores  of  the  soil  empty  above  it, 
the  air  follows,  and  fills  with  a  renewed  supply  the  numerous 
cavities  from  which  the  descent  of  the  rain  had  driven  it. 
Where  land  remains  full  of  water,  no  such  renewal  of  air  can 
take  place. 

2°.  It  warms  the  under  soil. — As  the  rain  falls  through  the 
air  it  acquires  the  temperature  of  the  atmosphere.  If  this  be 
higher  than  that  of  the  surface  soil,  the  latter  is  warmed  by  it; 


RAINS   WASH    OUT   NOXIOUS   MATTER.  145 

and  if  the  rains  be  copious,  and  sink  easily  into  the  subsoil, 
they  will  carry  this  warmth  with  them  to  the  depth  of  the 
drains.  Thus  the  under  soil  in  well  drained  land  is  not  only 
warmer,  because  the  evaporation  is  less,  but  because  the  raing 
in  the  summer  season  actually  bring  down  warmth  from  the 
heavens  to  add  to  their  natural  heat. 

3°.  It  eqibalises  the  temperature  of  the  soil  during  the  season  of 
growth. — The  sun  beats  upon  the  surface  of  the  soil,  and  gra- 
dually warms  it.  Yet,  even  in  summer,  this  direct  heat  descends 
only  a  few  inches  beneath  the  surface.  But  when  rain  falls 
upon  the  warm  surface,  and  finds  an  easy  descent,  as  it  does  in 
open  soils,  it  becomes  itself  warmer,  and  carries  its  heat  down 
to  the  under  soil.  Then  the  roots  of  plants  are  warmed,  and 
general  growth  is  stimulated. 

It  has  been  proved,  by  experiments  with  the  thermometer, 
that  the  under  as  well  as  the  upper  soil  is  warmer  in  drained 
than  in  undrained  land,  and  the  above  are  some  of  the  ways  by 
which  heat  seems  to  be  actually  added  to  soils  that  have  been 
thoroughly  drained. 

4°.  It  carries  down  sohMe  substances  to  the  roots  of  plants. — 
"When  rain  falls  upon  heavy  undrained  land,  or  upon  any  land 
into  which  it  does  not  readily  sink,  it  runs  over  the  surface,  dis- 
solves soluble  matter,  and  carries  it  into  the  nearest  ditch  of 
brook.     Bain  thus  robs  and  impoverishes  such  land. 

But  let  it  sink  where  it  falls — then  whatever  it  dissolves  it 
will  carry  downwards  to  the  roots — it  will  distribute  uniformly 
the  saUne  matters  which  have  a  natural  tendency  to  rise  to  the . 
surface,  and  it  will  thus  promote  growth  by  bringing  food  every- 
where within  the  reach  of  plants. 

5°.  It  washes  noxious  matters  from  the  under  soil.— ~ln  the  sub- 
soil, beyond  the  reach  of  the  air,  substances  are  apt  to  collect, 
especially  in  red-colored  soils,  which  are  injurious  to  the  roots 
of  plants.  These  the  descent  of  the  rains  alters  in  part  and 
makes  wholesome,  and  in  part  washes  out.  The  plough  may 
then  safely  be  trusted  deeper,  and  the  roots  of  plants  may 
1 


146  PROPORTION   OF   RAIN   EVAPORAlfii*. 

descend  in  search  of  food  where  they  wouM  previously  hare 
been  destroyed. 

It  is  true  that,  when  heavy  rains  fall,  they  will  also  wash  out 
of  the  soil  and  carry  into  the  drains  substances  which  it  would 
be  useful  to  retain.  Upon  this  fact  some  have  laid  unnecessary 
stress,  and  have  adduced  it  as  an  argument  against  thorough- 
drainage.  But  if  we  balance  the  constant  benefit  against  the 
occasional  evil,  I  am  satisfied,  as  experience  indeed  has  shown, 
that  the  former  wDl  greatly  preponderate. 

6° .  It  brings  down  fertilising  substances  from  the  air. — Besides, 
the  rains  never  descend  empty-handed.  They  constantly  bear 
with  them  gifts,  not  only  of  moisture  to  the  parched  herbage, 
but  of  organic  and  saline  food,  by  which  its  growth  is  promoted. 
Ammonia  and  nitric  acid,  (p.  33,)  together  with  the  many 
exhalations  which  are  daily  rising  from  the  earth's  surface, 
come  down  in  the  rains  ;  common  salt,  gypsum,  and  other  saline 
substances  derived  from  the  sea,  are  rarely  wanting  ;  and  thus, 
the  constant  descent  from  the  heavens  may  well  be  supposed  to 
counterbalance  the  occasional  washings  from  the  earth. 

I*.  Much  of  the  rain  is  evaporated. — And  lastly,  in  answer  to 
this  objection,  it  is  of  importance  to  state,  that  in  our  climate  a 
very  large  proportion  of  the  rain  that  falls  does  not  sink  through 
the  soil,  even  where  there  are  drains  beneath,  but  rises  again 
into  the  air  in  the  form  of  watery  vapor.  Experiments  in  Man- 
chester have  shown,  that  of  31  inches  of  rain  which  fall  there 
in  a  year,  24  are  evaporated  ;  while  in  Yorkshire,  of  24^  inches 
of  rain  which  fall,  only  5  inches  run  off  through  pipes  laid  at  a 
depth  of  2  feet  9  inches,  the  rest  being  evaporated.  There  is 
little  cause,  therefore,  for  the  fear  expressed  by  some,  that  the 
draining  of  the  land  will  cause  the  fertility  in  any  perceptible 
degree  to  diminish  in  consequence  of  the  washing  of  the  descend- 
ing rains.  They  may,  as  I  have  said,  improve  the  subsoil  by 
washing  hurtful  substances  out  of  it ;  but,  in  general,  the  soil 
will  have  extracted  from  the  water  which  filters  through  it  all 
the  valuable  matter  it  holds  in  solution  before  it  has  reached  the 
depth  of  a  3-feet  drain. 


CHAPTER  XI. 

Mechanical  methods  oontiuued. — The  subsoil-plough  and  the  fork. — ^How 
tkey  act  in  improving  the  soil. — Experiments  on  the  profit  of  subsoiling.— • 
How  deep  ploughing  and  trenching  improve  the  soil. — Chemical  and 
other  effects  of  common  ploughing. — Improvement  of  the  soil  by  mixing. 

After  the  land  has  been  laid  dry  by  drains,  other  mechanical 
modes  of  improvement  can  be  employed  with  advantage.  Even 
the  ordinary  methods  of  mechanical  culture  become  more  useful, 
and  the  benefits  which  in  favorable  circumstances  are  derived 
from  turning  up  the  soil  are  greater  and  more  manifest.  These 
facts  will  appear  by  a  brief  consideration  of  the  effects  produced 
by  ploughing  to  various  depths,  and  the  causes  from  which  they 
arise. 

SECTION  I. — USE  OF  THE  SUBSOIL-PLOUGH.      HOW  IT  ACTS  IN  IMPROV- 
ING THE  SOIL. 

The  subsoil-plough  is  an  auxiliary  to  the  drain — it  stirs  and 
opens  the  under  soil  without  mixing  it  with  the  upper  or  imme- 
diately active  soil.  Though  there  are  few  subsoils  through 
which  the  water  will  not  at  length,  make  its  way,  yet  there  are 
some  so  stiff,  either  naturally  or  from  long  consolidation,  that 
the  good  effect  of  a  well-arranged  line  of  drains  is  lessened  by 
the  slowness  with  which  they  allow  the  superfluous  water  to  pass 
through  them.  In  such  cases,  the  use  of  the  subsoil-plough  is  most 
advantageous  in  loosening  the  under  layers  of  soil,  and  in  allow- 
ing the  water  to  find  a  ready  escape  downwards  to  either  side, 
until  it  reaches  the  drains.* 

*  For  a  fuller  discussion  of  the  benefits  of  drainage,  see  the  Author'i 
Ledwres. 


148  HOW  THE   SUBSOIIrPLOUGH  ACTS. 

It  is  well'  known  that  if  a  piece  of  stiff  clay  be  cut  into  the 
shape  of  a  brick,  and  then  allowed  to  dry,  it  will  contract  and 
harden — ^it  will  form  an  air-dried  brick,  almost  impervious  to 
any  kind  of  air.  Wet  it  again,  it  will  swell  and  become  still 
more  impervious.  Cut  up  while  wet,  it  will  only  be  divided  into 
so  many  pieces,  each  of  which  will  harden  when  dry,  or  the 
whole  of  which  will  again  attach  themselves  and  stick  together 
if  exposed  to  pressure  while  they  are  still  wet.  But  tear  it 
asunder  when  dry  and  it  will  fall  into  many  pieces,  will  more  or 
less  crumble,  and  will  readily  admit  the  air  into  its  inner  parts. 
So  it  is  with  a  clay  subsoil. 

After  the  land  is  provided  with  drains,  the  subsoil  being  very 
retentive,  the  subsoil-plough  is  used  to  open  it  up — to  let  out 
the  water  and  let  in  the  air.  If  this  is  not  done,  the  stiff  under 
«lay  will  contract  and  bake  as  it  dries,  but  it  will  neither  suffi- 
ciently admit  the  air,  nor  open  so  free  a  passage  for  the  roots. 
Let  this  operation,  however,  be  performed  when  the  clay  is  still 
too  wet,  a  good  effect  will  follow  in  the  first  instance ;  but  after 
a  while  the  cut  clay  will  again  cohere,  and  the  farmer  will  pro- 
nounce subsoiling  to  be  a  useless  expense  on  his  land.  Defer 
the  use  of  the  subsoil-plough  till  the  clay  is  dry — ^it  will  then 
tear  and  hreak  instead  of  cutting  it,  and  its  openness  will  remain. 
Once  give  the  air  free  access,  and,  after  a  time,  it  so  modifies 
the  drained  clay  that  it  no  longer  has  an  equal  tendency  to 
cohere. 

Mr.  Smith  of  Deanston  very  judiciously  recommended  that 
the  subsoil-plough  should  never  be  used  till  at  least  a  year  after 
the  land  has  been  thoroughly  drained.  This  in  many  cases  will 
be  a  sufficient  safeguard — ^will  allow  a  sufficient  time  for  the 
clay  to  dry :  in  other  cases,  two  years  may  not  be  too  much. 
But  this  precaution  has  by  some  been  neglected;  and,  subsoil- 
ing being  with  them  a  failure,  they  have  sought,  in  some  sup- 
posed chemical  or  other  quality  of  their  soil,  for  the  cause  of  a 
want  of  success  which  is  to  be  found  in  their  own  neglect  of  a 
most  necessary  precaution.    Let  not  the  practical  man  be  too 


RESULTS  OP  EXPERIMENTS. 


149 


tlasty  in  desiring  to  attain  those  benefits  which  attend  the  adop- 
tion of  improved  modes  of  culture;  let  him  give  every  method  a 
fair  trial;  and  above  all,  let  him  make  his  trial  in  the  way  and 
with  the  precaution  recommended  hy  the  author  of  the  method,  before 
he  pronounces  its  condemnation. 


SECTION   II. 


-EXPERIMENT   ON   THE   PROFITS   OP   SUBSOILING. 
USE   OF   THE   FORK. 


The  benefits  of  subsoil  ploughing  having  been  sometimes 
called  in  question,  and  there  being  even  some  cases  on  record 
in  which  positive  injury  has  been  said  to  follow  from  the  prac- 
tice, I  introduce  the  following  numerical  results  observed  on 
two  farms  in  the  neighborhood  of  Penicuik,  a  few  miles  from 
Edinburgh. 

1°.  Mr.  Wilson  of  Eastfield,  Penicuik,  made  an  experiment, 
after  thorough  drainage,  upon  two  portions  of  land  under  each 
of  three  crops,  and  found  the  effects  in  the  first  year  after  sub- 
soil ploughing,  compared  with  ordinary  ploughing,  to  be  as 
follows : 


Ploughed  to  8  inches,  - 
Subsoiled  to  15  inches, 

Dififerehce, 

Turnips. 

Barley. 

Potatoes. 

Grain. 

Straw. 

tons.  cwt. 
20       7 
26      17 

qrs. 
7^ 
8g 

cwt. 
28 
36i 

tons.  cwt. 

6  144 

7  9i 

6      10 

i 

8i 

151 

1 

From  this  table,  the  effects  of  subsoiling  to  a  depth  of  15, 
above  that  of  ploughing  to  a  depth  of  8  inches,  appears  to  have 
been  to  increase  the  turnip  crop  by  6^  tons,  the  potatoes  by  15 
cwt.,  and  the  barley  by  1  bushels  of  grain  and  8  cwt.  of  straw. 

2°.  Mr.  Maclean  of  Braidwood,  near  Penicuik,  made  a  sim- 


150 


USE  OP  DEEP  PLOUGHING. 


ilar  experiment  with  tnmips  and  barley,  with  the  following 
results : — 


Ploughed  8  inches  deep,    -    - 
Subsoiled  to  16  inches,       -    - 

Difference,      -    - 

TUKNIPS. 

Barley. 

Grain. 

Straw. 

tons.      cwt. 
19         15 
23         17 

qrs. 
61 
71 

stonea. 
168i 
206i 

4            2 

1 

38 

The  turnip  crop,  in  this  experiment,  was  increased  4  tons ; 
and  the  barley  crop  by  6  bushels  of  grain  and  38  stones  of 
straw. 

It  has  been  observed-,  also,  that  the  effects  of  the  subsoiling  do 
not  cease  with  the  first  crop.  In  one  case,  in  which  an  accurate 
account  of  the  produce  was  kept,  the  profit  was  estimated  at  6s. 
an  acre,  for  five  successive  years  after  the  operation.  There  is 
reason,  therefore,  to  anticipate  general  good  from  the  careful 
introduction  of  this  practice  ;  though  it  is  exceedingly  desirable, 
at  the  same  time,  that  the  causes  of  its  failure,  wherever  it  is 
found  to  fail,  should  be  rigorously  investigated. 

The  use  of  the  fork,  instead  of  the  subsoil-plough,  has  lately 
been  recommended  as  a  more  efficient,  and  even  a  more  econom- 
ical method  of  opening  up  the  under  soil.  The  upper  soil  of  9 
to  12  inches  is  thrown  forward  with  a  spade,  and  the  under  soil, 
to  a  depth  of  15  inches  further,  is  stirred  and  turned  over  with 
a  three-pronged  fork.  I  have  seen  it  in  operation  ;  and  it  cer- 
tainly does  appear  to  loosen  and  open  up  the  under  soil  more 
effectually  than  the  subsoil  plough  can  do,  and  to  a  depth  which 
few  subsoil-ploughs  are  yet  able  to  reach. 


8ECTI0K   in. HOW  DEEP   PLOUGHING   AND  TRENCHING  IMPROVE  THE 

SOIL. 

1°.  Deep  ploughing,  like  subsoiling,  aids  the  effect  of  the 


LIME   AND   CLAY   SINK.  151 

drains,  and  so  far — ^where  it  goes  nearly  as  deep — even  more 
completely  effects  the  same  object.  But,  independently  of  this, 
it  has  other  uses  and  merits,  and,  where  it  has  been  successfully 
applied,  has  improved  the  land  by  the  operation  of  other  causes. 

Subsoiling  only  lets  out  the  water,  and  allows  access  to  the 
air  and  rains,  and  a  free  passage  to  the  roots.  Deep  ploughing, 
in  addition  to  these,  brings  new  earth  to  the  surface,  forms  thus 
a  deeper  active  soil,  and  more  or  less  alters  both  its  physical 
qualities  and  its  chemical  composition. 

If  the  plough  be  made  to  bring  up  2  inches  of  clay  or  sand, 
it  will  stiffen  or  loosen  the  soil,  as  the  case  may  be  ;  or  it  may 
affect  its  color  or  density.  It  is  clear  and  simple  enough,  there- 
fore, that  by  deep  ploughing,  the  physical  properties  of  the  soil 
may  be  altered. 

But  there  are  certain  substances  contained  in  every  soil, 
whether  in  pasture  or  under  the  plough,  which  gradually  make 
their  way  down  towards  the  subsoil.  They  sink  till  they  reach 
at  last  that  point  beyond  which  the  plough  does  not  usually  pen- 
etrate. Every  farmer  knows  that  lime  thus  sinks.  In  peaty 
soils  top-dressed  with  clay,  as  is  done  in  Lincolnshire,  the  clay 
thus  sinks.  In  sandy  soils,  also,  which  have  been  clayed,  the 
clay  sinks  :  and  in  all  these  cases,  I  believe,  the  sinking  takes 
place  more  rapidly  when  the  land  is  laid  down  to  grass.  Where 
soils  are  marled,  the  marl  sinks  ;  and  the  rains,  in  like  manner, 
gradually  wash  out  that  which  gives  their  fertilising  virtue  to 
the  large  doses  of  chalk  which  in  some  districts  are  spread  upon 
the  land,  and  render  necessary  a  new  application  to  renovate  its 
productive  powers. 

If  this  be  the  case  with  earthy  substances  such  as  those  now 
mentioned,  which  are,  for  the  most  part,  insoluble  in  water,  it 
will  be  readily  believed  that  those  saline  ingredients  of  the  soil 
which  are  easily  soluble,  will  be  still  sooner  washed  out  of  the 
upper  and  conveyed  to  the  imder  soil.  Thus  the  subsoil  may 
gradually  become  rich  in  those  substances  of  which  the  surface 
soil  has  been  robbed  by  the  rains.    Bring  up  a  portion  of  this 


152  BRINGING  UP  THE   SUBSOIL. 

subsoil  by  deep-ploughing,  and  you  restore  to  the  surface  soil  a 
part  of  what  it  has  been  gradually  losing — you  bring  up  what 
may  probably  render  it  more  fruitful  than  before.  Such  is  an 
outline  pf  the  reasons  in  favor  of  deep  ploughing. 

In  Germany,  theory  has  pointed  out  the  growing  of  an  occa- 
sional deep-rooted  crop  in  light  soils  to  effect  the  same  end.  The 
deep  roots  bring  up  again  to  the  surface  the  substances  which 
had  naturally  sunk. 

But  suppose  the  land  to  have  originally  contained  something 
noxious  to  vegetation,  which  in  process  of  time  has  been  wash- 
ed down  into  the  subsoil,  then  to  bring  this  again  to  the  sur- 
face would  be  materially  to  injure  the  land.  This  also  is  true, 
and  a  sound  discretion  must  be  employed,  in  judging  when  and 
where  such  evil  effects  are  likely  to  follow. 

Such  cases,  however,  are  more  rare  than  many  suppose. 
There  are  few  subsoils  which  after  a  year's  draining,  a  full  and 
fair  exposure  to  the  winter's  frost  will  not  in  a  great  degree  de- 
prive of  all  their  noxious  qualities,  and  render  fit  to  ameliorate 
the  general  surface  of  the  poorer  lands.  If  the  reader  doubt 
this  fact,  let  him  visit  Tester,  and  give  a  calm  consideration  to 
the  effects  produced  by  deep  ploughing  on  the  home  farm  of  the 
Marquis  of  Tweeddale.  Let  him  also  study  the  practice  of 
deep  ploughing,  as  it  is  followed  by  the  Jersey  farmers,  and  he 
will  be  still  further  persuaded  of  the  value  of  deep-ploughing, 
in  some  localities  at  least. 

In  many  cases  the  farmer  fears,  as  he  does  in  some'  parts  of 
the  county  of  Durham,  to  bring  up  a  single  inch  of  the  yellow 
clay  that  lies  beneath  his  surface  soil.  In  the  first  inch  lodges, 
among  other  substances,  the  iron  worn  from  his  plough,  which, 
in  some  soils,  and  after  a  lapse  of  years,  amounts  to  a  conside- 
rable quantity.  Till  it  is  exposed  to  the  air,  this  iron  is  hurt- 
ful to  vegetation  ;  and  one  of  the  benefits  of  a  winter's  expo- 
sure of  such  subsoils  to  the  air  arises  from  the  effect  produced 
upon  the  iron  th^y  contain. 

It  is  the  want  of  drainage,  however,  and  of  the  free  access 


COMMON   PIO.TJGHING.  153 

of  air,  that  most  frequently  renders  subsoils  for  a  time  injurious 
to  vegetation.  Let  the  lands  be  well  drained — let  the  subsoils 
be  washed  for  a  few  years  by  the  rain  water  passing  through 
them — and  there  are  few  of  those  which  are  clayey  in  their  na- 
ture that  may  not  ultimately  be  brought  to  the  surface,  not 
only  with  safety,  but  with  advantage  to  the  upper  soil. 

2°.  Trenching  with  the  spade  more  fully  and  effectually  per- 
forms what  the  trench-plough  is  intended  to  do.  The  spade 
more  completely  turns  over  the  soil  than  the  plough  does;  and, 
in  the  hands  of  an  industrious  laborer,  many  think  it  the  more 
economical  instrument  of  the  two. 

SECTION  IV. CHEMICAL  AND  OTHER  EFFECTS  OF  COMMON  PLOUGHING. 

Other  benefits,  again,  attend  upon  the  ordinary  ploughings, 
hoeings,  and  working  of  the  land.  Its  parts  are  more  mi- 
nutely divided — the  air  gets  access  to  every  particle — it  is  ren- 
dered lighter,  more  open,  and  more  permeable  to  the  roots. 
The  vegetable  matter  it  contains  decomposes  more  rapidly  by  a 
constant  turning  of  the  soil,  so  that  wherever  the  fibres  of  the 
roots  penetrate,  they  find  organic  food  provided  for  them,  and 
an  abundant  supply  of  the  oxygen  of  the  atmosphere  to  aid  in 
preparing  it.  The  production  of  ammonia  and  of  nitric  acid 
also,  (see  pages  26  to  32,)  and  the  absorption  of  these  and  of 
watery  Tapor  from  the  air,  take  place  to  a  greater  extent  the 
finer  the  soil  is  pulverised,  and  the  more  it  has  been  exposed  to 
the  action  of  the  atmosphere.  All  soils  contain,  hkewise,  an 
admixture  of  fragments  of  those  minerals  of  which  the  granitic 
and  trap  rocks  are  composed,  which,  by  their  decay,  yield  new 
supplies  of  inorganic  food  to  the  growing  plant.  The  more 
frequently  they  are  exposed  to  the  air,  the  more  rapidly  do 
these  fragments  crumble  away  and  decompose.  The  general 
advantage,  indeed,  to  be  derived  from  the  constant  working  of 
the  soil,  may  be  inferred  from  the  fact,  that  TuU  reaped 
twelve  successive  crops  of  wheat  from  the  same  land  by  the 


154  MIXING  THE   SOIL 

repeated  use  of  the  plough  and  the  horse-hoe.  Tlicre  are  few 
soils  so  stubborn  as  not  to  show  themselves  grateful  in  pro- 
portion to  the  amount  of  this  kind  of  labor  that  may  be  be- 
stowed upon  them. 

It  is  chiefly  because  the  spade  or  the  fork  divides  and 
separates  the  soil  more  completely,  or  to  a  greater  depth,  that 
larger  crops  have  been  obtained  in  many  districts  by  the  in- 
troduction of  spade  husbandry  than  by  the  ordinary  mode  of 
culture  with  the  plough.  But  all  these  benefits,  which  a 
thorough  working  of  the  soil  is  fitted  to  confer,  are  only  fully 
realised  where  the  land  is  naturally  dry,  or  by  artificial  drain- 
age has  been  freed  from  superfluous  water. 

SECTION  V. OP  THE  IMPROVEMENT  pP  THE  SOIL  BY  MIXING. 

It  has  been  already  shown  that  the  physical  properties  of 
the  soil  have  an  important  influence  upon  its  average  fertility. 
The  admixture  of  pure  sand  with  clay  soils  produces  an  alter- 
ation which  is  often  beneficial,  and  which  is  almost  wholly 
physical.  The  sand  opens  the  pores  of  the  clay,  and  makes  it 
more  permeable  to  the  air. 

The  admixture  of  clay  with  sandy  or  peaty  soils,  however, 
produces  both  a  physical  and  a  chemical  alteration.  The  clay 
not  only  consolidates  and  gives  body  to  the  sand  or  peat,  but 
it  also  mixes  with  them  certain  earthy  and  saline  substances, 
useful  or  necessary  to  the  plant,  which  neither  the  sand  nor 
peat  might  originally  contain  in  sufficient  abundance.  It  thus 
alters  its  chemical  composition  and  fits  it  for  nourishing  new 
races  of  plants. 

Such  is  the  case  also  with  admixtures  of  marl,  of  shell-sand, 
And  of  lime.  They  slightly  consolidate  the  sands  and  open  the 
clays,  and  thus  improve  the  mechanical  texture  of  both  kinds 
of  soil ;  but  their  main  operation  is  chemical  ;  and  the  almost 
universal  benefit  they  produce  depends  mainly  upon  the  new 
chemical  element  they  introduce  into  the  soil. 


WITH   CLAY,  SAND,  &C,  155 

It  is  a  matter  of  almost  universal  remark,  that  in  our  cli- 
mate, soils  are  fertile — clayey  or  loamy  soils,  that  is — only 
when  they  contain  an  appreciable  quantity  of  lime.  In  what- 
ever way  it  acts,  therefore,  the  mixing  of  lime  in  any  of  the 
forms  above  mentioned,  with  a  soil  in  which  little  or  no  lime 
exists,  is  one  of  the  surest  practical  methods  of  bringing  it 
nearer  in  composition  to  those  soils  from  which  the  largest 
returns  of  agricultural  produce  are  usually  obtained.  Some  of 
the  chemical  effects  of  lime  upon  the  soil  will  be  explained  in  a 
subsequent  chapter. 


CHAPTER  XII. 

Improvement  of  the  soil  by  planting  and  tlie  growth  of  wood. — Influence  of 
the  Scotch  fir  and  the  larch  on  the  val"ao  of  pasture. — Causes  of  such 
influence  of  growing  trees. — Improvement  by  laying  down  to  grass. — Ob- 
served facts. — Porras  wliich  the  improvement  assumes. — In  what  way 
pastures  generally  increase  in  value  by  age. — Agency  of  roots,  of  insects 
and  of  winds. — "Why  rich  pasture,  when  ploughed  up,  is  difficult  t« 
restore. 

There  are  certain  modes  of  improving  the  soil,  which,  though 
involving  only  simple  mechanical  operations  on  the  part  of  the 
improver,  produce  their  effects  through  the  agency  of  refined 
Bcientific  causes.  Such  are  the  improvements  produced  by 
planting  and  laying  down  to  grass.  These,  therefore,  I  shall 
briefly  consider  in  the  present  chapter, 

SECTION    I. IMPROVEMENT    OF   THE     SOIL    BY   PLANTING,    AND    HOW 

IT    IS    EFFECTED, 

It  has  been  observed  that  lands  which  ar^  unfit  for  arable 
culture,  and  which  yield  only  a  trifling  rent  as  natural  pasture, 
are  yet  in  many  cases  capable  of  growing  profitable  plantations, 
and  of  being  greatly  increased  in  permanent  value  by  the  pro- 
longed growth  of  wood.  Not  only,  however,  do  all  trees  not 
thrive  alike  on  the  same  soil,  but  all  do  not  improve  the  soil  on 
which  they  grow  in  an  equal  degree. 

Under  the  Scotch  fir,  for  example,  the  pasture  which  springs 
up  after  a  lapse  of  years  is  not  worth  6d,  more  per  acre  than 
before  the  land  was  planted ; — under  the  beech  and  spruce,  it  is 
worth  even  less  than  before,  though  the  spruce  afi'ords  excellent 
shelter} — ^under  the  ash,  it  gradually  acquires  an  increased  value 


IMPROVEMENT   BY   PLANTING.  151 

of  2s.  or  3s.  per  acre.  In  oak  copses,  it  becomes  worth  5s.  or 
6s.,  but  only  during  the  last  eight  years  (of  the  twenty-four) 
before  the  oak  copse  is  cut  down.  But  under  the  larch,  after 
the  first  thirty  years,  when  the  thinnings  are  all  cut,  land  not 
worth  originally  more  than  Is.  per  acre  becomes  worth  83.  to 
10s.  per  acre  for  permanent  pasture.* 

1.  The  main  cause  of  this  improvement  is  to  be  found  in  the 
nature  of  the  soil,  which  gradually  accumulates  beneath  the 
trees  by  the  shedding  of  their  leaves.  The  shelter  from  the  sun 
and  rain  which  the  foliage  affords,  prevents  the  vegetable  mat- 
ter which  falls  from  being  so  speedily  decomposed,  or  from 
being  so  much  washed  away,  and  thus  permits  it  to  collect  in 
larger  quantities  in  a  given  time  than  where  no  such  cover  ex- 
ists. The  more  complete  the  shelter,  therefore,  the  more  rapid 
will  the  accumulation  of  soil  be,  in  so  far  as  it  depends  upon 
this  cause. 

2.  But  the  quantity  of  leaves  which  annually  fall,  as  well  as 
the  degree  of  rapidity  with  which,  under  ordinary  circumstances, 
they  undergo  decay,  have  also  much  influence  upon  the  extent 
to  which  the  soil  is  capable  of  being  improved  by  any  given 
species  of  tree.  The  broad  leaves  of  the  beech  and  oak  decay 
more  quickly  than  the  needle-shaped  leaves  of  the  pine  tribes, 
and  this  circumstance  may  assist  in  rendering  the  larch  more 
valuable  as  a  permanent  improver, 

3.  We  should  expect,  hkewise,  that  the  quantity  and  quality 
of  the  inorganic  matter  contained  in  the  leaves  (p.  60) — brought 
up  year  by  year  from  the  roots,  and  strewed  afterwards  uni- 
formly over  the  surface  where  the  leaves  are  shed — would  ma- 
terially affect  the  value  of  the  soil  they  form.  The  dry  leaves 
of  the  oak,  for  example,  contain  about  5  per  cent  of  saline  and 
earthy  matter,  while  those  of  the  Scotch  fir  contain  less  than  2 
per  cent;  so  that,  supposing  the  actual  weight  of  leaves  which 
falls  from  each  kind  of  tree  to  be  equal,  we  should  expect  a 

*  The  result  of  triyls  made  on  the  mica  slate  and  gneiss  soils  (see  page 
101)  of  the  Dulr©  of  AtholL 


168  HOW  FALLEN  LEAVES  FERTILIZE. 

greater  depth  of  soil  to  be  formed  in  the  same  time  by  the  oak 
than  by  the  Scotch  fir.  The  leaves  of  the  larch  in  the  dry 
state  contain  from  5  to  6  per  cent  of  saline  matter,  so  that  they 
may  enrich  the  surface  on  which  they  fall  in  at  least  an  equal 
degree  with  those  of  the  oak.  Much,  hovrever,  depends  upon 
the  annual  weight  of  leaves  shed  by  each  kind  of  tree,  in  regard 
to  which  we  possess  no  precise  information. 

The  improvement  of  the  land,  therefore,  by  the  planting  of 
trees,  depends  in  part  upon  the  quantity  of  organic  food  which 
the  trees  can  extract  from  the  air,  and  afterwards  drop  in  the 
form  of  leaves  upon  the  soil,  and  in  part  upon  the  kind  and 
quantity  of  inorganic  matter  which  the  roots  can  bring  up  from 
beneath,  and  in  like  manner  strew  upon  the  surface.  The  quan- 
tity and  quality  of  the  latter  will,  in  a  great  measure,  determine 
the  kind  of  grasses  which  will  spring  up,  and  the  consequent 
value  of  the  pasture  in  the  feeding  of  stock.  In  the  larch 
forests  of  the  Duke  of  AthoU,  the  most  abundant  grasses  that 
spring  up  are  said  to  be  the  Holcus  mollis,  and  the  Holcus 
lanatus  (the  creeping  and  the  meadow  soft  grasses.) 

The  action  of  a  tree,  therefore,  in  improving  the  soil,  is  two- 
fold. 

1°.  It  causes  vegetable  matter  to  accumulate  on  the  surface; 
and, 

2°.  It  brings  up  from  beneath  certain  substances  which  are 
of  vital  importance  to  the  growth  of  plants,  but  of  which  the 
upper  soil  may  have  been  deficient. 

In  a  previous  chapter  I  have  described  the  black  earth  of 
Central  Russia,  which  presents  probably  the  most  remarkable 
example  now  existing  of  the  fertilising  effect  of  a  long-con- 
tinued growth  of  trees.  The  cotton  soil  of  Central  and  South- 
ern Hindostan  owes  its  richness  to  a  similar  cause. 


LAYING  DOWN   TO   GRASS.  159 


8BCTI0N  II. — IMPROVEMENT  OF  THE  SOIL  BY  LAYING  DOWN  TO  GRASS, 
FACTS  WHICH  HAVE  BEEN  ASCERTAINED. 

On  this  subject,  two  facts  seem  to  be  pretty  generally 
acknowledged. 

First,  That  land  laid  down  to  artificial  grasses  for  one,  two, 
three,  or  more  years,  is  in  some  degree  rested  or  recruited,  and 
is  fitted  for  the  better  production  of  after  crops  of  corn. 
Letting  it  lie  a  year  or  two  longer  in  grass,  therefore,  is  one  of 
the  received  modes  of  bringing  back  to  a  sound  condition 
a  soil  that  hag  been  exhausted  by  injudicious  cropping. 

Second,  That  land  thus  laid  down  with  artificial  grasses 
diminishes  in  value  again  after  two,  three,  or  five  years — more 
or  less — and  only  by  slow  degrees  acquires  a  thick  sward  of 
rich,  nourishing  natural  herbage.  Hence  the  opinion  that  grass 
land  improves  in  quality  the  longer  it  is  permitted  to  lie — the 
unwillingness  to  plough  up  old  pasture — and  the  comparatively 
high  rents  which,  in  some  parts  of  the  country,  old  grass  land  is 
known  to  yield. 

Granting  that  grass  land  does  thus  generally  increase  in  value, 
three  important  facts  must  be  borne  in  mind  before  we  attempt 
to  assign  the  cause  of  this  improvement,  or  the  circumstances 
under  which  it  is  likely  to  take  place  for  the  longest  time  and  to 
the  greatest  extent. 

1.  The  value  of  the  grass  in  any  given  spot  may  increase  for 
an  indefinite  period,  but  it  will  never  improve  beyond  a  certain 
extent — it  will  necessarily  be  limited,  as  all  other  crops  are,  by 
the  quality  of  the  land.  Hence  the  mere  laying  down  to  grass 
will  not  make  all  land  good,  however  long  it  may  lie.  The  ex- 
tensive commons,  heaths,  and  wastes,  which  have  been  in  grass 
from  the  most  remote  times,  are  evidence  of  this.  They  have, 
in  most  cases,  yielded  so  poor  a  natural  herbage  as  to  have 
been  considered  unworthy  of  being  enclosed  as  permanent  pas- 
ture. 


160  NATURE  OF  THE  IMPROVEMENT. 

2.  Some  grass-lands  will  retain  the  good  condition  they  thus 
slowly  acquire  for  a  very  long  period,  and  without  manuring — in 
the  same  way,  and  upon  nearly  the  same  principle,  that  some  rich 
corn-lands  have  yielded  successive  crops  for  100  years  without 
manure.  The  rich  grass-lands  of  England,  and  especially  of 
Ireland,  many  of  which  have  been  in  pasture  from  time  imme- 
morial, without  receiving  any  known  return  for  all  they  have 
yielded,  are  illustrations  of  this  fact. 

3.  But  others,  if  grazed,  cropped  with  sheep,  or  cut  for  hay, 
will  gradually  deteriorate,  unless  some  proper  supply  of  manure 
be  given  to  them — which  required  supply  must  vary  with  the 
nature  of  the  soil,  with  the  kind  of  stock  fed  upon  it,  and  with 
the  kind  of  treatment  to  which  it  has  been  subjected. 

SECTION  III. — FORM  WHICH   THE  IMPROVEMENT   ASSUMES,    AND   HOW 
IT    IS    BROUGHT   ABOUT. 

In  regard  to  the  acknowledged  benefit  of  laying  down  to  grass, 
then,  two  points  require  consideration. 

1°.  What  form  does  it  assume — and  how  is  it  effected  ? 

The  improvement  takes  place  by  the  gradual  accumulation 
of  a  dark-brown  soil  rich  in  vegetable  matter,  which  soil  thick- 
ens or  deepens  in  proportion  to  the  time  during  which  it  is 
allowed  to  lie  in  grass.  It  is  a  law  of  nature,  that  this  accu- 
mulation takes  place  more  rapidly  in  the  temperate  than  in 
tropical  climates,  and  it  would  appear  as  if  the  consequent 
darkening  of  the  soil  were  intended,  among  other  purposes,  to 
enable  it  to  absorb  more  of  the  sun's  warmth,  and  thus  more 
speedily  to  bring  forward  vegetation  where  the  average  tempe- 
rature is  low  and  the  summers  comparatively  short. 

If  the  soil  be  very  light  and  sandy,  the  thickening  of  the 
vegetable  matter  is  sooner  arrested  j  if  it  be  moderately  heavy 
land,  the  improvement  continues  for  a  longer  period ;  and  some 
of  the  heaviest  clays  in  England  are  known  to  bear  the  richest 
permanent  pastures. 


HOW  IT  IS  BROUGHT  ABOUT.  161 

The  soils  formed  on  the  surface  of  all  our  rich  old  pasture 
lands  thus  come  to  possess  a  remarkable  degree  of  uniformity 
— both  in  physical  character  and  in  chemical  composition. 
This  uniformity  they  gradually  acquire,  even  upon  the  stiff  clays 
of  the  lias  and  Oxford  clay,  which  originally,  no  doubt,  have 
been  left  to  natural  pasture — as  many  clay  lands  still  are — 
from  the  difficulty  and  expense  of  submitting  them  to  arable 
culture. 

2°.  How  do  they  acquire  this  new  character,  and  why  is  it 
the  work  of  so  much  time  ? 

a.  "When  the  young  grass  throws  up  its  leaves  into  the  air, 
from  which  it  derives  so  much  of  its  nourishment,  it  throws 
down  its  roots  into  the  soil  in  quest  of  food  of  another  kind. 
The  leaves  may  be  mown  or  cropped  by  animals,  and  carried 
off  the  field  ;  but  the  roots  remain  in  the  soil,  and,  as  they  die, 
gradually  fill  its  upper  part  with  vegetable  matter.  On  an 
average,  the  annual  production  of  roots  on  old  grass-land  is 
equal  to  one-third  or  one-fourth  of  the  weight  of  hay  carried 
off* — though  no  doubt  it  varies  much,  both  with  the  kind  of 
grass  and  with  the  kind  of  soil.  When  wheat  is  cut  down,  the 
quantity  of  straw  left  in  the  field,  in  the  form  of  stubble  and 
roots,  is  sometimes  greater  than  the  quantity  carried  off  in  the 
sheaf.  Upon  a  grass  field  two  or  three  tons  of  hay  may  be 
reaped  from  an  acre,  and  therefore,  from  half  a  ton  to  a  ton  of 
dry  roots  is  annually  produced  and  left  in  the  soil.  If  anything 
like  this  weight  of  roots  die  every  year,  in  land  kept  in  pasture, 
we  can  readily  understand  how  the  vegetable  matter  in  the  soil 
should  gradually  accumulate.  In  arable  land  this  accumulation 
is  prevented  by  the  constant  turning  up  of  the  soil,  by  which 
the  fibrous  roots,  being  exposed  to  the  free  access  of  air  and 
moisture,  are  made  to  undergo  a  more  rapid  decomposition. 

b.  But  the  roots  and  leaves  of  the  grasses  contain  earthy 
and  saline  matters  also.     Dry  hay  leaves  from  an  eighth  to  a 

*  See  the  Author's  Lectures  on  AgricvMural,  CJwmistry  and  Geology,  2d 
edition. 


162  CIRCUMSTANCES   BY  WRICE  IT  IS  PROMOTED. 

tenth  part  of  its  weight  of  ash  when  burned.  Along  with  the 
dead  vegetable  matter  of  the  soil,  this  inorganic  matter  also 
accumulates  in  the  form  of  an  exceedingly  fine  earthy  powder; 
hence  one  cause  of  the  universal  fineness  of  the  surface-mould 
of  old  grass-fields.  The  earthy  portion  of  this  inorganic  mat- 
ter consists  chiefly  of  silica,  lime,  and  magnesia,  with  scarcely 
a  trace  of  alumina  ;  so  that,  even  on  the  stififest  clays,  a  sur- 
face soil  may  be  ultimately  formed,  in  which  the  quantity  of 
alumina — the  substance  of  clay — is  comparatively  small. 

c.  There  are  still  other  agencies  at  work,  by  which  the  sur- 
face of  stiff  soils  is  made  to  undergo  a  change.  As  the  roots  of 
the  grasses  penetrate  into  the  clay,  they  more  or  less  open  up  a 
way  into  it  for  the  rains.  Now,  the  rains  in  nearly  all  lands, 
when  they  have  a  passage  downwards,  have  a  tendency  to  carry 
down  the  clay  along  with  them.  They  do  so,  it  has  been  ob- 
served, on  sandy  and  peaty  soils,  and  more  quickly  when  these 
soils  are  laid  down  to  grass.  Hence  the  mechanical  action  of 
the  rains — slowly  in  many  localities,  yet  surely — has  a  tendency 
to  lighten  the  surface  soil,  by  removing  a  portion  of  its  clay. 
They  constitute  one  of  those  natural  agencies  by  which,  as 
elsewhere  explained,  important  differences  are  ultimately  estab- 
lished, almost  everywhere,  between  the  surface  crop-bearing 
soil  and  the  subsoil  on  which  it  rests. 

d.  But  further,  the  heats  of  summer  and  the  frosts  of  winter 
aid  this  slow  alteration.  In  the  extremes  of  heat  and  of  cold, 
the  soil  contracts  more  than  the  roots  of  the  grasses  do  ;  and 
similar,  though  less  visible,  differences  take  place  during  the 
striking  changes  of  temperature  which  are  experienced  in  our 
climate  in  the  different  parts  of  almost  every  day.  When  the 
rain  falls,  also,  on  the  parched  field,  or  when  a  thaw  comes  on 
in  winter,  the  earth  expands,  while  the  roots  of  the  grasses  re- 
main nearly  fixed ;  hence  the  soil  rises  up  among  the  leaves, 
mixes  with  the  vegetable  matter,  and  thus  assists  in  the  slow 
accumulation  of  a  rich  vegetable  mould. 

The  reader  may  have  witnessed  in  winter  how,  on  a  field  or 


EFFECT  OP   EARTH-WORMS  AND  WINDS.  163 

by  a  way-side,  the  earth  rises  above  the  stones,  and  appears  in- 
clined to  cover  them  ;  he  may  even  have  seen,  in  a  deserted 
and  undisturbed  highway,  the  stones  gradually  sinking  and  dis- 
appearing altogether,  when  the  repetition  of  this  alternate 
contraction  and  expansion  of  the  soil  for  a  succession  of  winters 
has  increased,  in  a  great  degree,  the  effects  which  follow  from  a 
single  accession  of  frosty  weather. 

So  it  is  in  the  fields.  And  if  a  person  skilled  in  the  soils  of 
a  given  district  can  make  a  guess  at  the  time  when  a  given 
field  was  laid  down  to  grass,  by  the  depth  at  which  the  stones 
are  found  beneath  the  surface,  it  is  partly  because  this  loosen- 
ing and  expansion  of  the  soil,  while  the  stones  remain  fixed, 
tends  to  throw  the  latter  down  by  an  almost  imperceptible 
quantity  every  year  that  passes. 

e.  Such  movements  as  these  act  in  opening  up  the  surface 
soil,  in  mixing  it  with  the  decaying  vegetable  matter,  and  in 
allowing  the  slow  action  of  the  rains  gradually  to  give  its 
earthy  portion  a  lighter  character.  But  with  these,  among 
other  causes,  conspires  also  the  action  of  living  animals.  Few 
persons  have  followed  the  plough  without  occasionally  observ- 
ing the  vast  quantities  of  earth-worms  with  which  some  fields 
seem  to  be  filled.  On  a  close-shaven  lawn,  many  have  noticed 
the  frequent  little  heaps  of  earth  which  these  worms  during 
the  night  have  thrown  out  upon  the  grass.  These  and  other 
minute  animals  are  continually  at  work,  especially  beneath  an 
undisturbed  and  grassy  sward — and  they  nightly  bring  up  from 
a  considerable  depth,  and  discharge  on  the  surface,  their  bur- 
den of  fine  fertilising  loamy  earth.  Each  of  these  burdeus  is 
rfin  actual  gain  to  the  rich  surface  soil;  and  who  can  doubt 
that,  in  the  lapse  of  years,  the  unseen  and  unappreciated 
labors  of  these  insect  tribes  must  both  materially  improve  its 
quality  and  increase  its  depth  ?  * 

*  In  the  Prize  Essays  of  the  Highland  Society,  (vol.  1.  p.  191,)  the  reader 
will  find  the  testimony  of  a  practical  man  that  such  was  in  reality  the  case, 
as  observed  by  himself  on  part  of  his  own  farm  in  Roxburgshire. 


164  FOREST  TREES   ENRICH  THE  SOIL. 

/.  In  most  localities,  also,  tke  winds  may  be  mentioned  among 
the  natural  agencies  by  which  the  soil  on  grass  lands  is  slowly 
improved.  They  seldom  sweep  over  any  considerable  extent  of 
arable  land  without  bearing  with  them  particles  of  dust  and 
sand,  which  they  'drop  in  sheltered  places,  or  leave  behind  them 
when  sifted  by  the  blades  of  grass,  or  by  the  leaves  of  an  ex- 
tensive forest.  In  hot  summers,  in  dry  springs,  and  even  in 
winter,  when  the  snow  is  drifting,  the  ploughed  lands  and  dusty 
roads  are  more  or  less  bared  of  their  lighter  particles  of  soil, 
which  are  strewed  by  the  winds  as  a  natural  top-dressing  over 
the  neighboring  untilled  fields. 

In  some  countries  the  agency  of  the  winds  is  more  conspicuous 
than  among  ourselves.  Thus  on  the  banks  of  the  Kuruman  and 
Orange  rivers  in  South  Africa,  the  winds  blow  during  the  spring 
months — August  to  November  in  that  climate — from  the  Kular 
gare  desert,  bearing  with  them  light  particles  of  dust,  which 
make  the  air  seem  as  if  dense  with  smoke,  and  which  are  so  ex- 
quisitely fine  as  to  penetrate  through  seams  and  cracks  which 
are  almost  impervious  to  water.*  Forest  trees  and  waving 
grass  sift  this  thick  air  and  enrich  the  soils  on  which  they  grow 
by  the  earthy  particles  they  arrest. 

In  countries  where  active  volcanoes  exist,  these  also  exercise 
an  appreciable  influence  of  a  similar  kind  upon  the  surface  soil. 
Showers  of  dust  and  ashes  are  sprinkled  widely  over  the  land, 
by  which  its  natural  agricultural  capabilities  are  materially  in- 
terfered with.  Vesuvius  is  said,  in  this  way,  to  scatter  its  ashes 
over  the  adjoining  country,  so  as,  on  an  average,  to  destroy  the 
crop  every  eighth  year.     But  to  this  circumstance  the  remarka- 

I  have  lately  seen  a  notice  from  the  Carlisle  Jovmal  of  a  bowling-green* 
at  Penrith,  (45  yards  by  32,)  from  which,  after  watering  with  a  solution  of 
corrosive  sublimate,  eleven  stones  of  worms  were  this  year  gathered,  and 
four  years  ago  twenty  stones.  Tho  labors  of  such  a  number  of  animals  must 
produce  in  time  a  very  sensible  effect 

*  MoffaXs  Missionary  Labors,  p.  333. 


ALL  LAND   REQUIRES  ADDmONS.  165 

ble  general  richness  of  the  soil  is  ascribed — (Mohl.^  So  does 
good  arise  from  seeming  evil. 

There  are  natural  causes,  then,  which  we  know  to  be  at  work, 
that  are  sufficient  to  account  for  nearly  all  the  facts  that  have 
been  observed  in  regard  to  the  effect  of  laying  land  down  to 
grass.  Stiff  clays  will  gradually  become  lighter  on  the  surface, 
and,  if  the  subsoil  be  rich  in  all  the  kinds  of  inorganic  food 
which  the  grasses  require,  will  go  on  improving  for  an  indefinite 
period  without  the  aid  of  manure.  Let  them,  however,  be  de- 
ficient in,  or  let  them  gradually  become  exhausted  of  any  one 
kind  of  this  food,  and  the  grass  lands  will  either  gradually  dete- 
rioTate  after  they  have  reached  a  certain  degree  of  excellence, 
or  they  must  be  supplied  with  that  one  ingredient,  that  one  kind 
of  manure  of  which  they  stand  in  need.  It  is  doubtful  if  any 
pasture  lands  are  so  naturally  rich  as  to  bear  to  be  cropped  for 
centuries  without  the  addition  of  manure,  and  at  the  same  time 
without  deterioration.  Where  they  appear  to  be  so,  they  pro- 
bably receive  from  springs,  from  sea-drift,  or  from  some  other 
unobserved  source,  those  perennial  supplies  which  reason  pro- 
nounces to  be  indispensable. 

On  soils  that  are  light,  again — which  naturally  contain  little 
clay — the  grasses  will  thrive  more  rapidly,  and  a  thick  sward 
will  be  sooner  formed,  but  the  tendency  of  rains  to  wash  out  the 
clay  may  prevent  them  from  ever  attaining  that  luxuriance  which 
is  observed  upon  the  old  pastures  of  the  clay  lands. 

On  undrained  heaths  and  commons,  and  generally  on  any  soil 
which  is  deficient  in  some  fertilising  element,  neither  abundant 
herbage,  nor  good  crops  of  any  other  kind,  can  be  expected  to 
flourish.  Laying  such  lands  down,  or  permitting  them  to  remain 
in  grass,  may  prepare  them  for  by-and-by  yielding  ohe  or  two 
average  crops  of  corn,  but  cannot  be  expected  alone  to  convert 
them  into  valuable  pasture. 

Finally,  plough  up  the  old  pastures  on  the  surface  of  which 
this  light  and  most  favorable  soil  has  been  long  accumulating, 
and  the  heavy  soil  from  beneath  will  be  again  mixed  up  with  it, 


166  KATURAL  GRASSES   CHANGE. 

the  vegetable  matter  will  disappear  rapidly  by  exposure  to  the 
air  during  the  frequent  ploughings;  and,  if  again  laid  down  to 
grass,  the  slow  changes  of  many  years  must  again  be  begun 
through  the  agency  of  the  same  natural  causes,  before  it  become 
capable  a  second  time  of  bearing  the  same  rich  herbage  it  was 
known  to  nourish  while  it  lay  undisturbed. 

Many  have  supposed  that,  by  sowing  down  with  the  natural 
grasses,  a  thick  and  permanent  sward  may  at  once  be  obtained; 
and  on  light  loamy  land,  rich  in  vegetable  matters,  this  method 
may,  to  a  certain  extent,  succeed;  but,  on  heavy  land,  in  which 
stifiF  clay  abounds  and  vegetable  matter  is  defective,  disappoint- 
ment will  often  follow  the  sowing  of  the  most  carefully  selected 
seeds.  By  the  agency,  among  other  causes,  of  those  above 
adverted  to,  the  soil  gradually  changes,  so  that  it  is  unfit,  when 
first  laid  down,  to  bear  those  grasses  which,  ten  or  twenty  years 
afterwards,  will  spontaneously  and  luxuriantly  grow  upon  it. 
Nature  is  not  regulated  by  one  principle  in  the  growth  of  corn 
and  by  another  in  growing  grass ;  the  apparent  difierence  in  her 
procedure  arises  from  real  differences  in  our  practice. 


CHAPTER  XIII. 

Chemical  methods  of  improving  the  soil. — Use  of  manures. — Objects  of  the 
farmer. — ^Vegetable  manures. — Green  manuring. — Use  of  sea-weed. — Dry 
vegetable  substances. —  Straw. — Sawdust. — Bran. —  Brewers'  grains. — 
Malt-dust. — Rape-dust — Hemp,  poppy,  cotton,  and  cocoa-nut  cakes. — Use 
of  peat. — Peat  composts  and  tanners'  bark. — Use  of  vegetable  substances 
decomposed  by  art. — Charred  peat,  wood  charcoal,  soot,  coal-dust,  and 
coal-tar. — Relative  fertilising  and  money  values  of  different  vegetable 
manures. 

None  of  the  methods  of  improving  the  soil  which  have  been 
described  in  the  preceding  chapter  are  purely  mechanical.  They 
all  involve,  as  I  have  shown,  some  chemical  alterations  also, 
which  are  to  be  explained  only  by  a  knowledge  of  chemical 
principles.  But  the  manuring  of  the  land  is  more  strictly  a 
chemical  operation,  and  may  therefore  with  propriety  be  sepa- 
rated from  those  methods  of  improvement  which  involve  at  the 
same  time  important  and  expensive  mechanical  operations. 

In  commencing  the  tillage  of  a  piece  of  land,  the  conscien- 
tious farmer  may  have  three  objects  in  view  in  regard  to  it. 

1.  He  may  wish  to  reclaim  a  waste,  or  to  restore  a  neglected 
farm  to  an  average  condition  of  fertility. 

2.  Finding  the  land  in  this  average  state,  his  utmost  ambition 
may  be  to  keep  it  in  its  present  condition ;  or, 

3.  By  high  farming  he  may  wish  to  develop  all  its  capabili- 
ties, and  to  increase  its  permanent  productiveness  in  the  great- 
est possible  degree. 

The  man  who  aims  at  the  last  of  these  objects  is  not  only  the 
best  tenant  and  the  best  citizen,  but  he  is  also  his  own  best 


168  WHAT   IS   A   MANtTRE. 

friend.  The  highest  fanning,  skilfully  and  prudently  conduct- 
ed, is  also  the  most  remuneratinjr.* 

But  whichever  of  these  three  ends  he  aims  at,  he  will  be  un- 
able to  attain  it  without  a  due  knowledge  of  the  various 
manures  it  may  be  in  his  power  to  apply  to  his  land — what 
these  manures  are,  or  of  what  they  consist — the  general  and 
special  purposes  they  are  each  fitted  or  intended  to  serve — 
which  are  the  most  effective  for  this  or  that  crop,  and  why 
they  are  so — how  they  are  to  be  obtained  in  the  greatest 
abundance,  and  at  the  least  cost — how  their  strength  may  be 
economised — and  in  what  state  and  at  what  season  of  the  year 
they  may  be  most  beneficially  applied  to  the  land.  Such  are  a 
few  of  the  questions  which  the  skilful  farmer  should  be  ready 
to  ask  himself,  and  should  be  able  to  answer. 

By  a  manure  is  to  be  understood  whatever  is  capable  of 
feeding  or  of  supplying  food  to  the  plant.  And  as  plants  re- 
quire earthy  and  saUne  as  well  as  vegetable  food,  gypsum  and 
nitrate  of  soda  are  as  properly  called  manures  as  farmyard 
dung,  bone-dust,  or  nightsoil. 

Manures  naturally  divide  themselves  into  such  as  are  of  vege- 
table, of  animal,  and  of  mineral  origin,  I  shall  consider  these 
different  kinds  of  manure  in  successive  chapters. 

SECTION  I. OF  THE  USE  OF  VEGETABLE  MANURES. 

There  are  two  purposes  which  vegetable  manure  is  generally 

♦  A  eingular  illustration  of  this  feet  is  mentioned  as  observed  in  Hol- 
stein,  where  marl  is  extensively  applied  to  the  land.  Those  fields  which 
ore  marled  yield  a  much  larger  produce  than  before,  while  the  adjoiniqg 
fields,  which  are  left  unmarled,  give  a  less  return  than  when  all  were  un- 
marled ;  so  that  the  holder  of  the  latter  is  compelled  to  improve  by  marl- 
ing his  fields  also. — Spkengel. 

It  is  also  a  curious  but  important  observation,  that  when  light  land^ 
poor  in  vegetable  matter,  are  reclaimed  from  a  state  of  waste,  they  pay 
better  for  the  manure  added  to  them  every  succeeding  year ;  that  is,  the 
ridier  in  organic  matter  they  become. — Von  Voght. 


VEGETABLE   MANURES.  Ift9 

supposed  to  serve  when  added  to  the  soil — it  loosens  the  land, 
opens  its  pores,  and  makes  it  lighter  ;  and  it  also  supplies 
organic  food  to  the  roots  of  the  growing  plant.  It  serves,  how- 
ever, a  third  purpose.  It  yields  to  the  roots  those  saline  and 
earthy  matters,  which  it  is  their  duty  to  find  in  the  soil,  and 
which  exist  in  decaying  plants  in  a  state  more  peculiarly  fitted 
to  enter  readily  into  the  circulating  system  of  new  races. 

Decayed  vegetable  matters,  therefore,  are  in  reality  mixed 
manures,  and  their  value  in  enriching  the  land  must  vary  con- 
siderably with  the  kind  of  plants,  and  with  the  parts  of  those 
plants  of  which  they  are  chiefly  made  up.  This  depends  upon 
the  remarkable  diflFerence  which  exists  in  the  quantity  and  kind 
of  the  inorganic  matter  contained  in  diflferent  vegetable  sub- 
stances, as  indicated  by  the  ash  they  leave,  (see  pages  59  to 
69.)  Thus  if  1000  lb.  of  the  sawdust  of  the  willow  be  fer- 
mented and  added  to  the  soil,  they  will  enrich  it  by  the  addi- 
tion of  only  4|  lb.  of  saline  and  earthy  matter,  while  1000  lb. 
of  the  dry  leaves  of  the  same  tree,  fermented  and  laid  on,  will 
add  82  lb.  of  inorganic  matter.  Thus,  independent  of  the 
effect  of  the  organic  matter  in  each,  the  one  will  produce  a 
very  much  greater  effect  upon  the  soil  than  the  other,* 

There  are  several  states  in  which  vegetable  matter  is  collect- 
ed by  the  husbandman  for  the  purpose  of  being  applied  to  the 
land — such  as  the  green  state,  the  dry  state,  that  state  of  im- 
perfect natural  decay  in  which  it  forms  peat,  and  the  decom- 
posed state  of  charcoal,  &c.,  to  which  it  has  been  reduced  by 
art. 

SECTION  n. OP   GJIEEN    MANURING,  AND  OF   THE    USE  OF  SEA-WEED. 

When  grass  is  mown  in  the  field,  and  laid  in  heaps,  it  speed- 

*  It  is  owing,  in  part,  to  this  large  quantity  of  saline  and  other  inorganic 
matters  which  they  contain,  that  fermented  leaves  alone  form  too  strong  a 
dressing  for  flowor  borders,  and  that  gardeners  therefore  generally  mix  tliem 
up  into  a  compoet. 

8 


170  GREEN   MANURING. 

ily  heats,  ferments,  and  rots.  But,  if  turned  over  frequently  and 
dried  into  hay,  it  may  be  kept  for  a  great  length  of  time  without 
undergoing  any  material  alteration.  The  same  is  true  of  all 
other  vegetable  substances — they  all  rot  more  readily  in  the 
green  state.  The  reason  of  this  is,  that  the  sap  or  juice  of  the 
gf^een  plant  begins  very  soon  to  ferment  in  the  interior  of  the 
stem  and  leaves,  and  speedily  communicates  the  same  condition 
to  the  moist  fibre  of  the  plant  itself.  When  once  it  has  been 
dried,  the  vegetable  matter  of  the  sap  loses  this  easy  tendency 
to  decay,  and  thus  admits  of  long  preservation. 

The  same  rapid  decay  of  green  vegetable  matter  takes  place 
when  it  is  buried  in  the  soil.  Hence  the  cleanings  and  scour- 
ings  of  the  ditches  and  hedge-sides  form  a  compost  of  mixed 
earth  and  fresh  vegetable  matter,  which  soon  becomes  capable 
of  enriching  the  ground.  "When  a  green  crop  is  ploughed  into 
a  field,  the  whole  of  its  surface  is  converted  into  such  a  compost 
— the  vegetable  matter  in  a  short  time  decays  into  a  light, 
black  mould,  and  enriches  in  a  remarkable  degree,  and  fertilises 
the  soil. 

This  is  one  reason  why  the  success  of  wheat  after  clover,  or 
of  oats  after  lea,  depends  so  much  on  the  ground  being  well 
covered  when  first  ploughed  up. 

1°.  Green  manuring. — Hence  the  practice  of  green  manuring 
has  been  in  use  from  very  early  periods.  The  second  or  third 
crop  of  lucerne  was  ploughed  in  by  the  ancient  Romans — as  it 
still  is  by  the  modern  Italians.  In  Tuscany,  the  white  lupin  is 
ploughed  in — ^in  parts  of  France,  the  bean  and  the  vetch — in 
Germany,  borage — and  upon  sandy  soils  in  Holstein,  spurry. 
The  Madia  sativa  has  lately  been  tried  as  a  green  manure  in 
Silesia.  It  is  sown  in  June,  and  is  ploughed  in,  when  two  feet 
high,  in  October.  Sheep  do  not  eat  it ;  so  that  if  a  flock  of 
sheep  be  turned  in,  they  eat  up  the  weeds  and  trample  down  the 
madia,  after  which  it  is  easily  ploughed  in.  In  a  month  it  is 
rotten,  and  the  land  may  be  cross-ploughed,  and  the  winter  corn 
sown. 


TURNIP   LEAVES    AND   POTATO    TOPS   READILY    DECAY.  Ill 

In  French  Flanders,  two  crops  of  clover  are  cut,  and  the  third 
is  ploughed  in.  In  some  parts  of  the  United  States,  the  clover 
is  never  cut,  but  is  ploughed  in  as  the  only  manure  ;  in  other 
parts,  the  first  crop  is  cut  and  the  second  ploughed  in.  In  some 
of  the  northern  States,  Indian  corn  is  sown  upon  poor  lands,  at 
the  rate  of  4  to  6  bushels  an  acre,  and  two  or  sometimes  three 
such  crops  are  turned  in  during  the  summer.  In  north-eastern 
China,  a  species  of  coronilla  and  a  trefoil  are  specially  sown  and 
grown  in  ridges,  as  a  manure  for  the  rice  crop.  They  are 
ploughed  and  harrowed  in  before  the  young  rice  plauts  are  put 
into  the  flooded  land. 

In  Sussex,  and  in  parts  of  Scotland,  turnip  seed  has  been 
sown  at  the  end  of  harvest,  and  after  two  months  again  ploughed 
in,  with  great  benefit  to  the  land.  Wild  mustard,  also,  which 
grows  so  abundantly  as  a  weed  on  many  of  our  corn-fields,  is 
not  unfrequently  raised  for  ploughing  in  green.  White  mustard 
is  sown  in  Norfolk,  and  ploughed  in  as  a  preparation  for  wheat  ; 
sometimes,  also,  on  the  stubble,  as  a  preparation  for  turnips.  It 
is  said  to  destroy  the  wire-worm.  Turnip  leaves  and  potato  tops 
decay  more  readily  and  more  perfectly,  and  are  more  enriching 
when  buried  in  the  green  state.  It  is  a  prudent  economy,  there- 
fore, where  circumstances  admit  of  it,  to  bury  the  potato  tops 
on  the  spot  from  which  the  potatoes  are  raised.*  Since  the 
time  of  the  Romans,  it  has  been  the  custom  to  bury  the  cut- 
tings of  the  vine  stocks  at  the  roots  of  the  vines  themselves  ; 
and  many  vineyards  flourish  for  a  succession  of  years  without 
any  other  manuring.  In  the  Weald  of  Kent  the  prunings  of 
the  hop-vine,  chopped  and  dug  in,  or  made  into  a  compost  and 
applied  to  the  roots  of  the  hop,  give  a  larger  crop,  and  with 
half  the  manure,  than  when  they  are  burned  or  thrown  away, 
as  is  usually  done. 

*  By  taking  off  the  blossoms  of  potatoes — besides  the  usual  increase  of 
crop — the  tops  keep  green  till  the  potatoes  are  lifted.  Thus  much  green 
matter  is  obtained ;  and  if  this  be  made  into  manure,  and  appUed  to  the 
next  potato  crop,  it  is  said  to  raise  the  largest  produce  of  tubers. 


173  USB  or  SSA-WEED. 

Buckwheat,  rye,  winter  tares,  clover,  and  rape,  are  all  occa- 
sionally sown  in  this  country  for  the  purpose  of  being  ploughed 
in.  This  should  be  done  when  thejlower  has  just  begun  to  open, 
and,  if  possible,  at  a  season  when  the  warmth  of  the  air  and  the 
dryness  of  the  soil  are  such  as  to  facilitate  decomposition. 

That  the  soil  should  be  richer  in  vegetable  matter  after  this 
burial  of  a  crop  than  it  was  before  the  seed  of  that  crop  was 
sown,  and  should  also  be  otherwise  benefited,  will  be  understood 
by  recollecting  (see  page  36)  that  perhaps  three-fourths  of  the 
whole  organic  matter  we  bury  has  been  derived  from  the  air — 
that  by  this  process  of  ploughing  in,  the  vegetable  matter  is 
more  equally  diffused  through  the  whole  soil,  than  it  could  ever 
be  by  any  merely  mechanical  means — and  that  by  the  natural 
decay  of  this  vegetable  matter,  ammonia  and  nitric  acid  are,  to 
a  greater  extent,  (page  26  and  29,)  produced  in  the  soil,  and 
its  agricultural  capabilities  in  consequence  materially  increased. 
Indeed,  a  green  crop  ploughed  in  is  believed,  by  some  practical  men, 
to  enrich  the  soil  as  much  as  the  droppings  of  cattle  from  a  quantity 
of  green  food  three  times  as  great. 

These  considerations,  while  they  explain  the  effect  and  illus- 
trate the  value  of  green  manuring,  will  also  satisfy  the  intelligent 
agriculturist  that  there  exist  methods  of  improving  his  land 
without  the  aid  either  of  town  or  of  foreign  manures — and  that 
he  overlooks  an  important  natural  means  of  wealth  who  neglects 
the  green  sods  and  the  crops  of  weeds  that  flourish  by  his  hedge- 
rows and  ditches.  Left  to  themselves,  they  will  ripen  their 
seeds,  and  sow  them  annually  in  his  fields ;  collected  in  compost 
heaps,  they  will  materially  add  to  his  yearly  crops  of  corn. 

2°.  Use  of  seorweed. — Among  green  manures,  the  use  of  fresh 
sea-ware  deserves  especial  mention,  from  the  remarkably  fertilis- 
ing properties  it  is  known  to  possess,  as  well  as  from  the  great 
extent  to  which  it  is  employed  on  all  our  coasts.  The  agricul- 
tural produce  of  the  Isle  of  Thanet,  in  Kent,  is  said  to  have 
been  doubled  or  tripled  by  the  use  of  this  manure ;  the  farms  on 
the  Lothian  coasts  let  for  20s.  or  30s.  more  rent  per  acre  when 


SPECIAL  ACTION   OF  SEA-WEED.  113 

they  have  a  right  of  way  to  the  sea,  where  the  weed  is  thrown 
ashore;*  and  in  the  Western  Isles  the  sea-ware,  the  shell-marl, 
and  the  peat-ash,  are  the  three  great  natural  fertilisers,  to  which 
the  agriculture  of  this  remote  region  is  indebted  for  the  com- 
parative prosperity  to  which  it  has  in  some  of  the  islands  already 
attained. 

The  common  red  tangle,  which  grows  farther  out  at  sea,  is  in 
some  districts  preferred  as  a  manure  to  the  other  varieties  of 
sea-weed,  when  applied  green  or  made  into  compost.  At  Oban, 
on  the  west  coast  of  Scotland,  the  fishermen  bring  it  in  their 
boats  and  sell  it  on  the  shore  at  a  shilling  a  cart.  One  cart  is 
there  reckoned  equal  to  two  of  farmyard  dung  for  raising  pota- 
toes. Used  alone  for  this  crop,  it  gives  a  good  return,  but  gen- 
erally of  inferior  quality.f  On  the  south-east  coast  of  Fife, 
where  the  sea-weed  is  laid  on  the  stubble  at  the  rate  of  20  carts 
an  imperial  acre,  ploughed  in,  and  the  turnips  afterwards  raised 
with  half  dung,  the  clover  is  said  never  to  fail.  Laid  on  bean- 
stubble,  and  ploughed  in,  21  cart-loads  gave  in  Suffolk,  (1819,) 
three  times  as  much  wheat  as  5  bushels  of  salt  and  15  loads  of 
farmyard  manure  per  acre. 

Sea-weeds  decompose  with  great  ease  when  collected  in  heaps 
or  spread  upon  the  land.  During  their  decay  they  yield  not 
only  organic  food  to  the  plant,  but  saline  matters  also,  to  which 
much  of  their  eflScacy  both  on  the  grass  and  the  corn  crops  is 
no  doubt  to  be  ascribed. 

Especially  to  this  saline  matter  may  be  ascribed  the  benefi- 
cial influence  of  sea-weed  on  garden  asparagus,  originally  a  sea- 
side plant,  and  upon  fruits  like  raspberries,  which  contain  much 
alkaline  matter. 

*  In  this  locality  16  loads  of  sea-weed  are  reckoned  equal  to  20  tons  of 
farmyard  manure.  In  the  Island  of  Lewis  20  tons  of  sea- ware,  which  would 
yield  half  a  ton  of  kelp,  are  considered  to  be  ample  manure  for  a  Scotch  acre. 

f  The  potatoes  are  said  to  be  of  better  quality  when  the  sea- weed  is  put 
into  the  soil  and  covered  with  a  layer  of  earth,  upon  wliich  the  potatoes  are 
to  be  planted. 


1T4  DRY   VEGETABLE   MATTER   FOR   MANURING. 

The  value  of  sea-weed  as  a  manure  may  be  understood  from 
the  fact  that  the  fums  sardiarinus  leaves,  when  dry,  28" 6  per 
cent  of  ash,  and  contains  19'26 — say  20  per  cent — of  protein 
compounds.  In  its  recent  state  it  contains  16  percent  of  water, 
(Payen.) 

SECTION    III. — OP   manuring  WITH   DRY  VEGETABLE   MATTER. 

1.  Straw. — Almost  every  one  knows  that  the  sawdust  of  most 
common  woods  decays  very  slowly — so  slowly,  that  it  is  rare  to 
meet  with  a  practical  farmer  who  considers  it  worth  the  trouble 
to  mix  sawdust  with  his  composts.  This  property  of  slow  decay 
is  possessed  in  a  certain  degree  by  all  dry  vegetable  matter. 
Heaps  of  dry  straw  when  alone,  or  even  when  mixed  with 
earth,  will  ferment  with  comparative  difficulty,  and  with  great 
slowness.  It  is  necessary,  therefore,  to  mix  it,  as  is  usually 
done,  with  some  substance  that  ferments  more  readily,  and 
which  will  impart  its  own  fermenting  state  to  the  straw.  Ani- 
mal matters  of  any  kind,  such  as  the  urine  and  droppings  of 
cattle,  are  of  this  character  ;  and  it  is  by  admixture  with  these 
that  the  straw  which  is  trodden  down  in  the  farmyard  is  made 
to  undergo  a  more  or  less  rapid  fermentation. 

The  object  of  this  fermentation  is  twofold — first,  to  reduce  the 
particles  of  the  straw  to  such  a  minute  state  of  division,  that 
they  may  admit  of  being  diffused  through  the  soil  ;  and  second, 
that  the  dry  vegetable  matter  may  be  so  changed  by  exposure 
to  the  air  and  other  agencies,  as  to  be  fitted  to  yield  without 
difficulty  both  organic  and  inorganic  food  to  the  roots  of  the 
plants  it  is  intended  to  nourish. 

Differences  of  opinion  have  prevailed,  and  discussions  have 
taken  place,  as  to  the  relative  efficacy  of  long  and  short,  or  of 
half  fermented  and  of  fully  rotten  dung.  But  if  it  be  added 
solely  for  the  purpose  of  yielding  food  to  the  plant,  or  of  prepar- 
ing food  for  it,  the  case  is  very  simple.  The  more  complete  the 
state  of  fermentation,  if  not  carried  too  far,  the  more  immediate 


LOSS   OF   WEIGHT   BY    FERMENTATION.  175 

will  be  the  agency  of  the  manure — hence  the  propriety  of  the 
application  of  short  dung  to  turnips  and  other  plants  it  is  desir- 
able to  bring  rapidly  forward  ;  but  if  the  manure  be  only  half 
decayed,  it  will  require  tune  in  the  soil  to  complete  the  decom- 
position, so  that  its  action  will  be  more  gradual  and  prolonged. 

Though  in  the  latter  case  the  immediate  action  is  not  so  per- 
ceptible, yet  the  ultimate  benefit  to  the  soil,  and  to  the  crops, 
may  be  even  greater,  supposing  them  to  be  such  as  require  no 
special  forcing  at  one  period  of  the  year.  This  is  easily  under- 
stood. While  it  is  undergoing  fermentation  in  the  farmyard, 
the  straw  loses  part  of  its  substance — either  in  the  state  of 
gaseous  matter,  which  escapes  into  the  air — or  of  saline  matter, 
which  is  washed  out  in  the  liquid  form.  Thus,  after  complete 
fermentation,  the  quantity  of  matter  present  is  really  less,  and' 
consequently,  when  added  to  the  soil,  though  the  immediate 
effect  upon  the  crop  be  greater,  the  whole  effect  may  also  be 
very  considerably  less. 

This  will  appear  more  clearly  when  it  is  considered  that  the 
quantity  of  recent  dung — mixed  straw  and  cow  dung — is  by 
experiment  equal  on  an  average  to  2  or  2^  times  that  of  the 
dry  food  and  fodder  taken  together,  while,  when  fully  rotten, 
the  weight  of  the  dung  may  be  no  greater  than  that  of  the  dry 
food  and  fodder  consumed  by  the  cattle. 

Thus  it  has  been  found  that  one  ton  (20  cwt.)  of  dry  food 
and  straw  gives  a  quantity  of  farmyard  dung  which  weighs, 


"When  recent, 

46  to  50  cwt 

After  6  weeks, 

40  to  44    .. 

After  8  weeks, 

38  to  40    ., 

When  half  rotten, 

30  to  35    . . 

When  fully  rotten, 

20  to  25    .. 

A  part  of  this  loss  may,  no  doubt,  be  ascribed  to  the  evapora,- 
tion  of  a  portion  of  the  water  of  the  recent  dung  ;  but  the 
larger  part  is  due  to  an  actual  escape  of  the  substance  of  the 
manure  itself.  The  farmer,  therefore,  who  applies  the  manure 
from  a  given  weight  of  food  and  straw,  in  a  fresh  state,  adds 


176  SAWDUST   AND    BRAN, 

more  to  his  land  than  if  he  first. allows  it  to  become  perfectly 
fermented.  Were  he  to  chop  his  straw,  and  put  it  in  as  it 
comes  fresh  from  the  field,  he  would  add  still  more  ;  but  its  ac- 
tion as  a  manure  would  be  slower,  and  while  it  would  benefi- 
cially open  stiflF  and  heavy  soils,  it  would  injure  others,  by 
rendering  them  too  light  and  porous. 

2.  Sawdust. — With  a  view  to  this  slow  amelioration,  dry 
vegetable  matter  of  any  kind  may,  if  in  a  sufficient  state  of  di- 
vision, be  added  with  benefit  to  the  soil.  Even  sawdust, 
applied  largely  to  the  land,  has  been  found  to  improve  it, — 
little  at  first,  more  during  the  second  year  after  it  was  applied, 
still  more  during  the  third,  and  most  of  all  in  the  fourth  season 
after  it  was  mixed  with  the  soil.  That  any  dry  vegetable  mat- 
ter, therefore,  does  not  produce  an  immediate  effect,  ought  not 
to  induce  the  practical  farmer  to  despise  the  application  to  his 
land — either  alone  or  in  the  form  of  a  compost — of  everything 
of  the  kind  he  can  readily  obtain.  If  his  fields  are  not  already 
very  rich  in  vegetable  matter,  both  he  and  they  will  be  ulti- 
mately benefited  by  sucJh  additions  to  the  soil. 

Saturated  with  ammoniacal  liquor,  or  with  liquid  manure, 
sawdust  has  been  profitably  used,  and  without  further  addition, 
in  the  raising  of  turnips.  It  may  also  be  charred  either  by 
burning,  or  by  alternate  layers  of  quick-lime,  and  thus  benefi- 
cially applied. 

8.  Bran. — The  bran  and  pollard  of  wheat  are  highly  recom- 
mended as  manures.  Drilled  in  with  the  turnip  seed  at  the  rate 
of  5  or  6  cwt.  an  acre,  at  a  cost  of  £1  2s.  6d.,  it  brought  the 
young  plants  rapidly  forward,  and  gave  one-third  more  in 
weight  of  bulbs  than  the  other  parts  of  the  field,  which  had 
been  treated  in  the  same  way  in  every  respect,  except  that  no 
addition  of  bran  had  been  made  to  them.  If  moistened  with 
urine  and  slightly  fermented,  the  action  of  bran  would  no 
doubt  be  hastened  and  rendered  more  powerful. 

The  husk  of  the  oat,  hitherto  wasted  at  many  of  the  oatraea 


MALT  AND  RAPE  DUST.  171 

mills  in  the  north,  might  also  be  beneficially  fermented  and  em- 
ployed as  a  manure. 

4.  Brewers'  grains,  though  usually  given  as  food  to  fattening 
cattle  or  to  milch  cows,  are  by  some  of  the  farmers  in  Norfolk 
employed  as  a  manure.  They  are  supposed  to  pay  best  when 
mixed  with  farmyard  manure. 

5.  Malt-dust — cummins,  or  combings — consists  of  the  dried 
sprouts  of  barley,  which,  when  the  sprouted  seed  is  dried  in  the 
process  of  malting,  break  off  and  form  a  coarse  powder.  This 
is  found  to  be  almost  equal  to  rape-dust  in  fertilising  power. 
One  hundred  bushels  of  barley  yield  105  to  110  of  malt  and  4 
to  5  of  dust.  In  this  neighborhood  (Durham)  it  is  sold  at  one 
shilling  a  bushel. 

Applied  in  the  dry  state,  malt-dust  decomposes  slowly,  and 
from  its  extreme  lightness  is  appUed  with  difficulty,  as  a  top- 
dressing.  If  it  be  moistened  with  liquid  manure  and  laid  in 
heaps  for  a  few  days  till  it  heat  and  begin  to  ferment,  it  may 
be  used  either  as  a  top-dressing  for  grass,  clover,  and  young 
corn,  or  it  may  be  drilled  in  with  the  seed.  It  may  also  in  this 
state  be  employed  with  advantage  without  any  other  manure 
for  the  turnip  or  potato  crop ;  but  the  turnip-seed  should  not  be 
brought  into  immediate  contact  with  it  in  the  drills. 

Malt-dust  leaves,  when  dry,  8  per  cent  of  ash,  and  contains 
23  per  cent  of  protein  compounds,  (Payen.)  This  composition 
explains  both  its  fertilising  action  when  applied  to  the  soil,  and 
its  nourishing  effects  when  given  to  cattle  or  sheep  along  with 
turnips. 

6.  Jtape-dust. — It  is  from  the  straw  of  the  corn-bearing  plants, 
or  from  the  stems  and  leaves  of  the  grasses,  that  the  largest 
portion  of  the  strictly  vegetable  manures  applied  to  the  soil  is 
generally  obtained  or  prepared.  But  the  seeds  of  all  plants  are 
much  more  enriching  than  the  substance  of  their  leaves  and 
stems.  These  seeds,  however,  are  in  general  too  valuable  for 
food  to  admit  of  their  application  as  a  manure.  Still  the  re- 
fuse of  some — as  that  of  different  kinds  of  rape-seed  after  the 

8* 


118  HEMP,   POPPY,   AND   COTTON   CAKES. 

oil  is  expressed,  and  which  is  unpalatable  to  cattle — is  applied 
with  great  benefit  to  the  land.  Drilled  in  with  the  winter  or 
spring  wheat,  or  scattered  as  a  top-dressing  in  spring  at  the 
rate  of  5  cwt.  an  acre,  it  gives  a  largely  increased  and  remune- 
rating return.  Applied  at  a  cost  of  40s.  per  acre  to  wheat,  it 
has  been  known  to  increase  the  produce  10  bushels  an  acre 
(from  29  to  39  bushels)  and  to  give  one-fifth  more  straw.  Nor 
is  the  practice  recent,  for  the  application  of  it  in  this  way,  and 
at  a  cost  of  40s.  to  42s.  an  acre,  was  common  in  Norfolk  in  the 
time  of  Arthur  Young,  (1710,)  eighty  years  ago. 

In  some  districts  it  is  used  largely,  and  without  admixture, 
for  the  raising  of  turnips.  It  is  applied  with  equal  success  to 
the  cultivation  of  potatoes,  if  it  be  put  in  the  place  of  a  part 
only  of  the  manure.  If  used  alone  it  is  apt  to  give  very  large 
and  luxuriant  tops,  with  only  an  inferior  weight  of  tubers.  It 
is  safer,  therefore,  to  mix  it  with  other  manure;  and  generally 
it  may  be  substituted  for  it  at  the  rate  of  about  1  cwt.  of  rape- 
dust  for  each  ton  of  farmyard  manure. 

1.  Hemp,  poppy,  and  cotton  cakes — the  refuse  of  crushed 
hemp,  poppy,  or  cotton  seed — may  be  used  for  similar  purposes, 
and  in  the  same  way,  as  rape-cake. 

8.  Cocoa-nut  cake,  left  by  the  expressed  cocoa-nut,  is  also  a 
valuable  manure,  and  has  alone  been  found  to  produce  large 
crops  of  potatoes. 

These  different  kinds  of  cake  all  contain  a  large  per-centage 
of  nitrogen,  (4  to  4^  per  cent,)  or,  in  other  words,  of  protein 
compounds.  These  ferment  very  easily,  promote  growth  ra- 
pidly, and  give  to  the  manures  that  contain  them  peculiar 
fertilismg  virtues. 

SECTION   IV. OP  THE   USE   OF   PEAT,  PEAT  COMPOST,  AND  TANNER'S 

BARK. 

1.  Natural  peat. — In  many  parts  of  the  world — and  in  none 
more  abundantly,  perhaps,  than  in  some  parts  of  our  own  islands 


PEAT,    NATURAL   AND    FERMENTKD.  1T9 

— ^vegetable  matter  continually  accumulates  in  the  form  of  peat. 
This  peat  ought  to  supply  an  inexhaustible  store  of  organic 
matter  for  the  amelioration  of  the  adjacent  soils.  We  know- 
that  by  draining  off  the  sour  and  unwholesome  water,  and 
afterwards  applying  lime  and  clay,  the  surface  of  peat  bogs  may 
be  gradually  converted  into  rich  corn-bearing  lands.  It  must, 
therefore,  be  possible  to  convert  peat  itself  by  a  similar  process 
into  a  compost  fitted  to  improve  the  condition  of  other  soils. 

2.  Fermented  peat. — The  late  Lord  Meadowbank,  who  made 
many  experiments  on  this  subject,  found,  that  after  being  par- 
tially dried  by  exposure  to  the  air,  peat  might  be  readily  fer- 
mented, and  brought  into  the  state  of  a  rich  fertilising  compost, 
by  the  same  means  which  are  adopted  in  the  ordinary  ferment- 
ing of  straw.  He  mixed  with  it  a  portion  of  animal  matter, 
which  soon  communicated  its  own  fermenting  quality  to  the  sur- 
rounding peat,  and  brought  it  readily  into  a  proper  heat.  He 
found  that  one  ton  of  hot  fermenting  manure,  mixed  in  alternate 
layers  with  two  of  half-dried  peat,  and  covered  by  a  layer  of 
the  same  peat,  was  sufficient  to  ferment  the  whole.  He  observed 
afterwards,  also,  that  the  vapors  which  rise  from  naturally 
fermenting  farmyard  manure  or  animal  matters,  would  alone 
produce  the  same  effect  upon  peat,  placed  so  as  readily  to 
receive  and  absorb  them. 

As  ammonia  is  one  of  the  compounds  specially  given  off  by 
putrefying  animal  substances,  it  is  not  unlikely  that  a  watering 
with  ammoniacal  liquor  would  materially  prepare  the  peat  for 
undergoing  fermentation.  At  all  events,  it  seems  possible  to 
prepare  any  quantity  of  valuable  peat  compost  by  mixing  the 
peat  with  a  little  soil,  and  with  a  still  smaller  quantity  of  fer- 
mented manure  than  was  employed  by  Lord  Meadowbank,  pro- 
yided  the  liquid  manure  of  the  farmyard  be  collected  into  a 
cistern,  and  be  thrown  at  intervals,  by  means  of  a  pump,  over 
the  prepared  heaps. 

After  being  partially  dried,  natural  peat  may  be  very  benefi- 


180  PEAT  COMPOST  :  CHARRED  PEAT. 

cially  employed  in  absorbing  the  liquid  manure  of  the  fannyard, 
or  in  mixing  with  the  contents  of  the  tanks. 

3.  Mr.  Fleming's  peat  compost. -^M&ny  other  ways  of  working 
up  peat  have  been  suggested,  such  as  adding  lime,  salt,  and 
other  substances,  to  aid  the  fermentation.  The  most  successful 
of  these  mixtures  with  which  I  am  acquainted  is  one  which  has 
been  used  with  much  advantage  on  the  home  farm  of  Mr.  Flem- 
ing of  Barochan.     This  compost  consists  of — 

Sawdust,  or  dry  earthy  peat,          -           -  40  bushels. 

Coal-tar,     .            -            ...  20  gallons. 

Bone-dust,              ....  7  bushels. 

Sulphate  of  soda,   -            .            <•            .  1  cwt. 

Sulphate  of  magnesia,        -            -            -  IJ  " 

Common  salt,         -            -            -            -  li  " 

Quick-lime,            -           -           •           -  20  bushels. 

These  materials  are  mixed  together  and  put  into  a  heap,  and 
allowed  to  heat  and  ferment  for  three  weeks,  then  turned,  and 
allowed  again  to  ferment,  when  the  compost  is  ready  for  use. 

Compared  with  farmyard  manure  and  guano,  this  mixture 
gave  on  hay  and  turnips — 

1°.  On  hay  per  imperial  acre. 

Produce.  Cost 
Nothing,        -           -    .                    416  stones. 

Guano,  3  cwt.            •            -            152    ...  $7  50 

Compost,  40  bushels,                         761    ...  6  00 

2°.  On  turnips,  (Jones'  yellow  top.) 

Produce.  Cost 
Farmyard  manure,  28  yards,           26  tons. 

Guano,  5  cwt.        .                .          18    . .  $12  50 

Compost,  64  bushels,              .         29    ..  1  li 

According  to  these  results,  this  compost  is  superior  even  to 
guano.  The  experiments,  however,  require  repetition,  and  the 
results  will  no  doubt  vary  with  the  kind  of  soil  and  of  crop  to 
which  the  compost  is  applied. 

4.  Charred  peat. — By  being  built  up  and  charred  or  half 
burned  in  covered  heaps,  peat  may  be  obtained  in  a  state  in 


USE   OF   CHARCOAL   POWDER.  "  181 

which  it  is  easily  reduced  to  powder.  In  this  powdery  state, -it 
has  been  used  alone  for  turnips,  at  the  rate  of  50  bushels  an 
acre,  and  was  found  to  give  as  good  a  crop  as  50  carts  of  farm- 
yard dung.  Something  of  this  action,  however,  may  have  de- 
pended upon  the  nature  of  the  soil,  and  upon  the  kind  of  peat. 
Charred  peat  forms,  likewise,  an  excellent  absorbent  for  the 
liquids  of  the  farmyard  and  the  stable,  and  for  drying  up  dis- 
solved bones. 

5,  Tanners'  hark. — I  may  here  advert  also  to  the  use  of  tan- 
ners' bark,  a  form  of  vegetable  matter  which,  like  sawdust  and 
peat,  is  difficult  to  work  up,  and  is  therefore  often  permitted 
largely  to  go  to  waste.  Like  peat  it  may  be  dried  and  burned 
for  the  ash,  which  is  light,  portable,  and  forms  a  valuable  top- 
dressing.  But  the  economist  will  prefer  to  ferment  it  in  a 
compost,  in  the  way  above  described  for  peat.  An  occasional 
watering  of  the  compost  with  the  liquid  manure  of  the  farm- 
yard will  bring  it  into  a  heat,  and  when  the  ammoniacal  liquor 
of  the  gas-works  can  be  procured  at  a  cheap  rate,  it  may  be 
employed  for  a  similar  purpose.  The  hard  thick  fragments  of 
bark,  however,  cannot  be  so  soon  decomposed  as  the  already 
finely  divided  peat,  and  must  be  expected  therefore  to  demand 
more  time.  "With  lime  it  may,  like  sawdust  or  peat,  be  reduced 
and  charred. 

SECTION  V, ^MANURING  WITH  ARTIFICIALLY  DECOMPOSED  VEGETABLK 

SUBSTANCES CHARCOAL,  SOOT,  COAL-TAR,    &C. 

When  wood  and  other  vegetable  substances  are  heated  in 
close  vessels  they  are  converted  into  charcoal.  Coal,  which  is 
of  vegetable  origin,  deposits  in  our  chimneys,  when  burned, 
large  quantities  of  soot  ;  and  when  distilled  in  gas-retorts  it 
yields,  besides  gas,  a  quantity  of  coal-tar  and  other  products. 
All  these  substances  have  been  tried  and  recommended  as  ma- 
nures. 

1°.  Charcoal  powder  possesses  the  remarkable  properties  of 


16S  EXPERIMENTS   WITH    SOOT. 

absorbing  noxious  vapors  from  the  air  and  from  the  soil,  and  of 
extracting  unpleasant  impurities  as  well  as  saline  substances 
from  water,  and  of  decomposing  many  saline  compounds.  It 
also  sucks  into  its  pores  much  oxygen  and  other  gases,  from  the 
air.  Owing  to  these  and  other  properties,  it  forms  a  valuable 
mixture  with  liquid  manure,  nightsoil,  farmyard  manure,  ammo- 
niacal  liquor,  or  other  rich  applications  to  the  soil.  It  is  even 
capable  itself  of  yielding  slow  supplies  of  nourishment  to  living 
plants  ;  and  it  is  said  in  many  cases,  even  when  unmixed,  to  be 
used  with  advantage  as  a  top-dressing  in  practical  agriculture.* 
In  moist  charcoal  the  seeds  of  the  gardener  are  found  to  sprout 
with  remarkable  quickness  and  certainty  ;  but  after  they  have 
sprouted,  they  do  not  continue  to  grow  well  in  charcoal  alone. 
Drilled  in  with  the  seed,  charcoal  powder  is  said  greatly  to 
promote  the  growth  of  wheat. 

2°.  Soot,  whether  from  the  burning  of  wood  or  of  coal,  con- 
sists chiefly  of  a  finely  divided  charcoal,  possessing  the  proper- 
ties above  mentioned.  It  contains,  however,  ammonia,  gypsum, 
nitric  acid,  and  certain  other  substances  in  considerable  quan- 
tity, to  which  its  well-known  effects  upon  vegetation  are  chiefly 
to  be  ascribed.  In  many  localities  it  increases  the  growth  of 
the  grass  in  a  remarkable  degree,  and  as  a  top-dressing  to 
wheat  and  oats,  it  sometimes  produces  effects  equal  to  those 
which  follow  the  use  of  the  nitrates  of  potash  or  soda.f 

Thus  wheat  and  oats  dressed  with  soot,  in  comparison  with 
undressed,  gave  the  following  return  of  grain — 


Wheat. 

Oats. 

Undressed, 

44:  bushels. 

49  bushels. 

Dressed, 

54       ,. 

65       .. 

Increase,  .10  6 

*  This  may  no  doubt  be  in  part  owing  to  its  aiding  the  production,  as  all 
jporous  substances  do,  of  ammonia  in  its  interior,  and  hence  of  apocrenate  of 
ammonia  (p.  23)  in  the  soil,  but  in  part  also  to  its  power  of  decomposing 
other  substances. 

f  Journal  of  the  Royal  AgriadtwraX  Society  of  England,  iL  p.  259. 


COAL  DUST  AND  COAL  TAR.  183 

It  acts  also  upon  root  crops — 56  bushels  of  soot  mixed  with  6 
of  common  salt  having  produced  larger  crops  of  carrots  than  24 
tons  of  farmyard  manure,  with  24  bushels  of  bones.* 

I  have  lately  examined  several  varieties  of  soot,  and  find 
that  it  contains  from  18  to  48  per  cent  of  mhieral  matter,  con- 
sisting of  earthy  substances  from  the  coal  carried  up  into  the 
chimney  by  the  draught,  and  of  gypsum  and  sulphate  of  mag- 
nesia derived  from  the  lime  of  the  flue  and  the  sulphur  of  the 
coal.  It  contains  besides  from  1  to  2  per  cent  of  ammonia, 
chiefly  in  the  state  of  sulphate.  These  proportions  of  ammonia, 
calculated  in  the  state  of  sulphate  of  ammonia,  are  equal  to 
from  5 1  to  12  per  cent  of  the  whole  weight  of  the  soot.  It  is 
not  wonderful,  therefore,  that  its  efi'ects  should  resemble,  and 
even  rival,  those  of  the  nitrate  of  soda  and  of  the  sulphate  of 
ammonia. 

When  applied  to  grass  in  spring  it  is  said  to  give  a  peculiar 
bitterness  to  the  pasture,  and  even  to  impart  a  taste  to  the 
milk.  Hence,  in  large  towns,  the  cow-feeders  of  the  milk- 
dairies  are  unwilling  to  purchase  early  grass  which  has  been 
manured  with  soot. 

3°.  Coal-dust. — In  the  county  of  Durham  the  dust  of  com- 
mon coal,  such  as  is  sifted  out  at  the  mines  as  too  small  for 
burning,  has  been  spread  upon  poor,  cold,  arable  land,  and  as 
a  top-dressing  upon  old  pastures,  with  manifest  advantage. 
Something  will,  no  doubt,  depend  both  upon  the  quality  of  the 
coal  and  upon  the  kind  of  land  to  which  it  is  applied. 

4°.  Coal-tar  applied  to  the  wheat-stubble  with  a  water-cart, 
at  the  rate  of  180  gallons  to  the  imperial  acre,  and  allowed  to 
remain  two  or  three  months  before  it  is  ploughed  in,  is  said 
greatly  to  benefit  the  after  crop  of  roots.  It  has  been  tried 
on  a  sandy  loam,  and  on  a  deep  clay.  It  has  also  been  used 
in  the  form  of  compost. 

*J(ywrnai  of  (he  Royai  Agricviturai  Society  of  England,  iv.  pv  270 


184 


DIFFERENT  VEGETABLE  MANURES. 


SECTION  VI. 


-RELATIVE  FERTILISING  AND  MONEY  VALUES    OP 
DIFFERENT  VEGETABLE  MANURES, 


There  are  two  principles  on  which  the  relative  values  of  dif- 
ferent vegetable  substances,  as  manures,  may  be  estimated  ; — 
first,  by  the  relative  quantity  and  kind  of  inorganic  matter  they 
respectively  contain  ;  and  second,  by  the  relative  proportions  of 
nitrogen  present  in  each. 

1.  Valued  according  to  the  quantity  of  inorganic  matter  they 
contain,  the  worth  of  the  several  kinds  of  straw,  hay,  &c., 
would  be  represented  by  the  following  numbers  :  A  ton  weight 
of  each  substance,  when  made  into  manure — provided  nothing 
is  washed  out  by  the  rains — will  return  to  the  soil  the  following 
quantities  of  inorganic  matter  in  pounds :- 


Wheat-straw, 

TO  to  360 

Oat-straw,    . 

100  to  180 

Hay, 

100  to  200 

Barley-straw, 

100  to  120 

Pea-straw,    . 

100  to  110 

Bean-straw, 

100  to  130 

Rye-straw,   . 

50  to  100 

Dry  potato-tops. 

400 

Dry  turnip-tops. 

370 

Rape,  and  other  cakea. 

120 

Malt-dust,     . 

180 

Dried  sea-weed. 

560 

Generally,  perhaps,  these  numbers  will  give  the  reader  a  tolera- 
bly correct  idea  of  the  relative  permanent  effects  of  the  above 
different  kinds  of  vegetable  matter,  when  laid  upon  the  soil. 
But  a  reference  to  the  facts  stated  in  pp.  64  to  73,  in  regard  to 
the  quality  of  the  inorganic  matter  contained  in  plants,  will  sat- 
isfy him  that  the  effect  of  these  manures  on  particular  crops  is 
not  to.be  judged  of  solely  by  the  absolute  quantity  of  earthy 
and  saline  matter  they  contain.  What  the  turnip-top,  for 
example,  or  the  bean-stalk,  returns  to  the  soil,  may  not  be 
exactly  what  will  best  promote  the  growth  of  wheat. 


EFFECTS   OP   THEIR   NITROGEN    ON    THEIR   VALUE. 


185 


2.  On  the  other  hand,  if  the  fertilising  value  of  vegetable 
substances  is  to  be  calculated  from  the  relative  quantities  of  ni- 
trogen they  severally  contain,  we  should  place  them  in  the  fol- 
lowing order  ; — the  number  opposite  to  each  substance  repre- 
senting that  weight  of  it  in  pounds  which  would  produce  the 
same  effect  as  100  pounds  of  farmyard  manure,  consisting  of 
the  mixed  droppings  and  litter  of  cattle.     (Boussingault.) 


Equivalent 

quantities  in 

pounds. 

Farmyard  manure,    .           .           .           . 

100 

Wheat-straw, 

80  to  170 

Oat-straw,     .... 

150 

Barley-straw, 

180 

Buckwheat-straw,     . 

85 

Pea-straw,    .... 

45 

"Wheat-cliaflF, 

50 

Green  grass. 

80 

Potato-tops,              ... 

75 

Fresh  sea-weed, 

80 

Dried  sea-weed. 

20 

Bran  of  wheat  or  Indian  com, 

26   . 

Malt-dust,     . 

13 

Rape,  and  other  cakes, 

8 

Fir  sawdust, 

250 

Oak  sawdust. 

180 

Coal-soot,     . 

20  to  30 

This  table  again  presents  the  same  substances  in  a  somewhat 
different  order  of  value  ;  showing,  for  example,  not  only  that 
such  substances  as  rape-dust,  malt-dust,  and  soot,  should  pro- 
duce a  much  more  remarkable  effect  upon  vegetation  than  the 
same  weight  even  of  farmyard  manure,  but  also  that  certain 
dry  vegetables,  such  as  bran,  chaff,  and  pea-straw,  will  yield, 
when  not  unduly  fermented,  a  more  enriching  manure  than  the 
straw  of  barley,  oats,  or  wheat.  It  agrees  also  with  the  known 
effect  of  green  manuring  upon  the  land,  since  80  pounds  of 
meadow  grass  ploughed  in  should,  according  to  the  tahle,  be  equal 
in  virtue  ^o  100  of  farmyard  manure. 

Some  writers  ascribe  the  entire  action  of  these  manures  to  the 


186  GENERAL   CONCLUSIONS. 

nitrogen  they  contain.  This,  however,  is  taking  a  one-sided 
view  of  their  real  natural  operation.  The  nitrogen,  during  their 
decay,  is  liberated  chiefly  in  the  form  of  ammonia, — a  compar- 
atively evanescent  substance,  producing  an  immediate  effect  in 
hastening  or  carrying  farther  forward  the  growth  of  the  plant, 
but  not  remaining  permanently  in  the  soil.  The  reader,  there- 
fore, will  form  an  opinion  consistent  alike  with  theory  and  with 
practice,  if  he  concludes — 

1.  That  the  immediate  effect  of  vegetable  manures  in  hasten- 
ing the  growth  of  plants  is  dependent,  in  a  great  degree,  upon 
the  quantity  of  nitrogen  they  contain  and  give  off  during  their 
decay  in  the  soil ;  but — 

2.  That  their  permanent  effect  and  value  is  to  be  estimated 
chiefly  by  the  quantity  and  quality  of  the  inorganic  matter  they 
contain — of  the  ash  they  leave  when  burned. 

The  effect  of  the  nitrogen  may  be  nearly  expended  in  a  sin- 
gle season;  that  of  the  earthy  and  saline  matters  may  not  be 
exhausted  for  several  years.  * 

Nor  is  the  carbon  of  vegetable  substances  without  its  im- 
portant uses  to  vegetation.  From  the  statements  contained  in 
the  earlier  chapters  of  the  present  work — especially  in  reference 
tiO  the  production  of  ammonia  and  nitric  acid  in  the  soil, 
through  the  agency  of  decaying  carbonaceous  matter — it  may 
be  inferred  that,  however  much  influence  we  may  allow  to  the 
nitrogen  and  to  the  earthy  matter  of  plants  in  aiding  the 
growth  of  future  races,  the  soundest  view  is  that  which  con- 
siders each  of  the  elements  present  in  decayed  or  decaying  plants  to 
be  capable  either  of  ministering  to,  or  of  preparing  food  for,  such 
as  are  still  alive.  We  may  not  be  able  as  yet  to  estimate  the 
precise  importance  of  each  element  to  any  particular  kind  of 
crop  or  soil,  or  so  to  adjust  the  quantities  of  each  in  our 
manures,  as  to  promote  the  growth  of  that  crop  upon  that  soil, 
in  the  greatest  possible  degree,  yet  the  principle  itself  is  a 
sound  one,  and  will  hereafter  guide  us  to  safe  and  correct 
•esults. 


CHAPTER  XIV. 

Animal  manures. — Flesh,  fish,  shell-fish. — Insects. — Blood. — Animalised 
charcoal. — Skiu,  horn,  hair,  wool. — "Woollen  rags. — Shoddy. — Horn-saw- 
dust, and  hoof  parings. — Cause  of  the  fertilising  influence  of  tliese  ma- 
nures.— Composition  and  use  of  bones  and  horn-flints. — Preparation  of 
dissolved  bones. — Comparative  experiments  with  crushed  and  dissolved 
bones. — Why  solution  in  acid  makes  bones  more  active. — Comparative 
action  of  flesh,  blood,  horn,  woollen  rags  and  bones. — Use  of  the  liquid 
excretions  of  animals. — Urine  of  man,  the  cow,  the  horse,  and  the  pig. — 
Coustructiou  of  liquid-manure  tanks. — Urate. — Sulphated  -orine. 

The  animal  substances  employed  as  manures  consist  chiefly 
of  the  flesh,  blood,  bones,  horns,  and  hair  of  sea  and  land  ani- 
mals, and  of  the  solid  and  liquid  excrements  of  land  animals 
and  birds. 

SECTION   I. — OF  FLESH,    FISH,  BLOOD,  AND  SKIN,  AND  OF   THEIR  USE 
AS  MANURES. 

Animal  substances,  in  general,  act  more  powerfully  as  ma- 
nures than  vegetable  substances;  it  is  only  the  seeds  of  plants 
which  can  be  at  all  compared  with  them  in  efficacy. 

1.  ThQJlesh  of  animals  is  rarely  used  as  a  manure,  except  in 
the  case  of  dead  horses  or  cattle  which  cannot  be  used  for 
food, 

2.  Fish  are,  in  this  country,  chiefly  applied  in  the  form  of 
the  refuse  of  the  herring  and  pilchard  fisheries,  though  occa- 
sionally such  shoals  of  sprats,  herrings,  dog-fish,  and  even 
mackerel,  have  been  caught  on  our  shores,  as  to  make  it  neces- 
sary to  employ  them  as  manure.  These  recent  animal  sub- 
stances are  found  to  be,  for  the  most  part,  too  strong  when 
applied  directly  to  the  land;  they  are  usually,  therefore,  made 


188  FISH  AS  A  MANURB. 

into  a  compost,  with  a  large  quantity  of  soil.  Five  barrels  ef 
fish,  or  fish  refuse,  made  into  twenty  loads  of  compost,  will  be 
sufficient  for  an  acre. 

On  the  coast  of  Norfolk,  large  quantities  of  sprats  are  used  as  a 
manure  for  the  turnip  crop.  They  are  sold  for  about  8d.  a  bushel. 
A  ton  and  a  half,  mixed  with  twelve  to  fifteen  cwt.  of  mould 
taken  from  the  head  of  the  field,  makes  a  compost  which  is  suffi- 
cient for  an  imperial  acre,  and  is  said  never  to  fail.  On  the 
shores  of  Aberdeenshire,  dog-fish  are  caught  and  applied  as  a 
manure. 

In  Rhode  Island  and  the  adjoining  States,  considerable  quan- 
tities of  manure  are  made  by  mixing  the  fish  called  menhaden, 
of  which  large  numbers  are  taken  in  the  bays,  with  peat  or 
swamp  mud,  in  the  proportion  of  one  load  of  fish  to  ten  of  peat 
or  mud.  As  many  as  t50  tons  of  this  fish  have  been  taken  at 
a  single  haul,  and  sold  to  the  farmers  at  about  2s.  6d.  the  thou- 
sand fish,  or  waggonload.*  On  the  coasts  of  Connecticut  large 
quantities  of  fish,  called  white  fish,  are  caught  and  sold  for 
manure,  at  the  rate  of  about  a  dollar  (4s.)  a  thousand,  weigh- 
ing 15  or  20  cwt.  They  are  either  laid  on  the  land  and  ploughed 
in,  or  are  made  into  a  compost.  In  the  north  of  China,  prawns 
and  other  kinds  of  fish  are  collected  and  employed  for  manuring 
purposes. 

The  refuse  of  the  fish  oils,  of  the  fat  of  animals  that  has  been 
melted. for  the  extraction  of  the  tallow,  of  skins  that  have  been 
boiled  for  the  manufacture  of  glue — as  also  horns,  hair,  wool, 
woollen  rags,  and  all  similar  substances,  when  made  into  com- 
posts— exercise,  in  proportion  to  their  weight,  a  much  greater 
influence  upon  vegetation  than  any  of  the  more  abundant  forms 
of  vegetable  matter. 

3.  Shdl-fish,  when  they  abound  on  our  coasts,  have  been  found 
to  be  capable  of  Economical  application  to  the  land,  even  for 
raising  turnips  and  potatoes.    They  are  mixed  with  a  little 

*  See  the  Author's  Notes  on  North  America,  voL  il  p.  231. 


INSECTS   AND   BLOOD.  ■    189 

earth  into  a  rich  compost,  and  allowed  slightly  to  ferment.  If 
the  means  of  crushing  them  be  at  hand,  their  vaiae  is  by  this 
process  considerably  increased.  On  the  northern  shores  of  the 
Solway,  near  Annan,  the  common  mussel  is  found  in  such  quan- 
tities in  some  places,  that,  when  the  tide  recedes,  a  cart-load 
can  be  raked  out  of  the  sand  in  so  short  a  time  as  to  make  it 
a  very  economical  manure.  The  Rev.  Mr.  Gillespie  of  Cum- 
mertrees  informs  me,  that  TOO  cart-loads  were  collected  and 
applied  to  the  raising  of  turnips  during  the  year  1844.  They 
are  used  without  other  manure,  at  the  rate  of  about  50  bushels 
to  the  Scotch  acre.  On  the  coasts  of  Lincolnshire,  also,  they 
are  met  with  in  some  places  in  large  quantities,  and  collected 
for  use  as  a  manure. 

4.  Even  the  bodies  of  insects  in  many  parts  of  the  world  form 
important  manures.  In  warm  climates,  a  handful  of  soil  some- 
times seems  almost  half  made  up  of  the  wings  and  skeletons  of 
dead  insects  :  in  Hungary  and  Carinthia  the  peasant  occasionally 
collects  as  many  as  30  cart-loads  of  dead  marsh-flies  in  a  single 
year  ;  and  in  the  richer  soils  of  France  and  England,  where 
worms  and  other  insects  abound,  the  presence  of  their  remains 
in  the  soil  must  aid  its  natural  productiveness. 

5,  Blood  is  in  this  country  very  seldom  applied  to  the  land 
directly.  Like  the  other  parts  of  animals,  however,  it  makes 
an  excellent  compost.  In  Northamptonshire,  such  a  compost  is 
made  by  mixing  about  50  gallons  of  blood  with  8  bushels  of 
peat-ashes  and  charcoal  powder,  and  allowing  the  mixture  to 
stand  for  a  year  or  two.  On  light  soils,  this  compost  raises 
excellent  turnips  when  applied  alone,  at  the  rate  of  6  quarters 
(48  bushels)  per  imperial  acre — or  of  2  quarters  with  12  tons 
of  farmyard  dung.  As  a  top-dressing  to  young  wheat,  20  or  30 
bushels  an  acre  greatly  increase  the  crop.  On  heavy  and  wet 
lands,  its  effects  are  less  perceptible.  In  that  part  of  England 
the  blood  is  contracted  for  at  the  rate  of  3d.  a  gallon.  In  some 
countries  the  blood  is  dried,  and  in  the  state  of  powder  is  applied 
«B  a  top-dressing  to  the  growing  crops.     In  this  state  it  is  sold 


190  WOOLLEJf   RAGS   AND   SHODDY. 

iu  Paris  at  about  Ss,  a  cwt. — a  moderate  price,  if  it  be  toler» 
biy  dry.  Samples  prepared  in  London,  and  containing  still  22 
per  cent  of  water,  have  also  been  valued  at  £S  or  £9  a  ton. 
But  this  mode  of  using  blood  is  not  very  widely  adopted. 

6.  Animalised  charcoal. — As  blood  comes  from  the  sugar  re- 
fineries, however — in  which,  with  lime-water  and  animal  char- 
coal, it  is  employed  for  the  refining  of  sugar — it  has  obtained 
a  very  extensive  employment,  especially  in  the  south  of  France. 
This  animal  black,  or  animalised  charcoal,  as  it  is  sometimes 
called,  contains  about  20  per  cent  of  blood,  and  has  risen  to 
such  a  price  in  France  that  the  sugar  refiners  actually  sell  it 
for  more  than  the  unmixed  blood  and  animal  charcoal  originally 
cost  them.  This  has  given  rise  to  the  manufacture  of  artificial 
mixtures  of  charcoal,  fecal  matters,  and  blood,  which  are  also 
Bold  under  the  name  of  animalised  charcoal.  A  great  disad- 
vantage attending  the  use  of  these  artificial  preparations  is, 
that  they  are  liable  to  be  adulterated,  or,  for  cheapness,  pre- 
pared in  a  less  efficient  manner. 

T.  Skin. — Fragments  of  skin  are  sometimes  used  as  a  ma- 
nure. The  parings  of  skins  from  the  tan-works  are  boiled  by 
the  glue-makers,  and  the  insoluble  refuse  is  sold  as  a  manure. 
This  refuse,  in  the  form  of  compost,  ought  to  nourish  the  crops 
very  much.  When  used  alone  for  potatoes,  it  is  said  to  make 
them  waxy  on  soils  where,  with  other  manures,  they  grow  mealy 
and  dry. 

SECTION   II. OF  HAIR,  WOOL,  WOOLLEN   RAGS,    SHODDY,   HORN-SAW- 

DUST,  AND  HOOF-PARINGS. 

1.  Horn,  hair,  and  wool,  depend  for  their  efficacy  precisely  ou 
the  same  principles  as  the  blood  and  flesh  of  animals.  They 
dififer  chiefly  in  this,  that  they  are  dry,  while  blood,  flesh,  and 
fish  contain  about  80  per  cent  of  their  weight  of  water. 
Hence,  one  ton  of  horn-shavings,  of  hair,*  or  of  dry  woollen 

*  In  China,  the  hair,  which  every  ten  days  is  shaven  from  the  heads  of  the 
«Qtire  population,  ie  collected  and  ^Id  for  manure  throughout  the  empire. 


NITROGEN    IN   ANIMAL   MANURES.  19! 

rags,  ought  to  enrich  the  soil  as  much  as  4  to  5  tons  of  blood. 
In  consequence,  however,  of  their  dryness,  the  horn  and  wool 
decompose  much  more  slowly  than  the  blood.  Hence  the  effect 
of  soft  animal  matters  is  more  immediate  and  apparent,  while 
that  of  hard  and  dry  substances  is  less  visible,  but  continues 
for  a  much  longer  period  of  time. 

2.  Woollen  rags,  when  made  into  a  compost  and  fermented, 
form  an  excellent  manure  for  potatoes  or  turnips.  In  the  hop 
countries,  they  are  buried  at  the  roots  of  the  hop  plants  with 
great  advantage.  They  sell  at  about  £b  a  ton.  On  the  sandy 
land  in  Wiltshire,  they  are  frequently  used  as  a  manure  for 
turnips. 

3.  Shoddy,  or  mill-waste — the  waste  of  the  woollen  and 
cloth  mills  of  Yorkshire — is  nearly  the  same  thing  as  hair  and 
woollen  rags.  It  sells  at  about  £2  a  ton,  and  is  extensively 
used  by  the  farmers  of  Kent  and  Northampton. 

4.  Horn-sawdust  and  hoof -parings. — The  small  dust,  parings, 
turnings,  and  siftings  of  horn  from  the  shops  of  the  comb-makers, 
as  well  as  the  hoofs  of  cattle,  are  now  sold  to  the  prussiate  of 
potash  manufacturers  at  the  rate  of  about  £2  a  ton.  If  they 
were  free  from  admixture,  they  should  be  worth  to  the  farmer 
about  the  same  price  as  woollen  rags.  They  are  usually  mixed 
with  much  sand  and  dust — amounting  sometimes  to  50  or  60 
per  cent  of  their  whole  weight.  In  this  state  they  are  not 
worth  more  than  two-fifths  of  the  price  of  dry  hair  or  woollen 
rags.  They  may  be  used  instead  of  bones  for  the  turnip  or 
potato  crop,  but  should  be  made  into  a  fermented  compost 
before  they  are  employed  as  a  top-dressing. 

SECTION  XL— CAUSE  OF  THE    FERTILISING   INFLUENCE  OF  THE  ABOVE 
ANIMAL  MANURES. 

The  fertilising  influence  of  the  parts  of  animal  bodies,  described^ 
in  the  preceding  sections,  depends  mainly  upon  their  consisting, 
for  the  greater  part,  of  substances  very  rich  in  nitrogen.     Thus — 


193  HORK  AKD  BONES. 

Pferoeniage  of 
nitrogen. 
Dry  blood,  flesh,  and  fish  contain  about    .  .  15J 

Dry  skin,  hair,  wool,  horns,  and  hoofs,       .  .    16  to  17  if 

But  these  two  classes  of  substances  differ  much  in  the  quaa- 
tity  of  water  they  contain — 

Percentage 
of  water. 
Blood,  fish,  and  flesli,  contain      .  .  .        78  to  82 

Hair,  wool,  and  horn,      .  .  .  .        10  to  15 

Skin  and  hoofs  vary  much  in  dryness,  and  therefore  the  aver- 
age proportion  of  water  in  them  cannot  be  estimated. 

The  special  differences  of  the  above  substances  as  manures 
depend  mainly  upon  those  differences  in  the  proportion  of  water. 
Blood,  fish,  and  flesh  decompose  rapidly,  act  quickly,  and  pro- 
mote growth  speedily.  Wool,  hair,  and  horn  take  a  long  time 
to  rot,  are  not  so  well  adapted,  therefore,  for  promoting  speedy 
growth,  but  by  their  gradual  decay  are  better  fitted  to  afford 
prolonged  nourishment  to  a  crop  which  continues  long  in  the 
ground,  or  permanently  to  enrich  a  soil  which  has  been  exhausted 
by  too  severe  cropping. 

The  mineral  matter  contained  in  these  substances  is  small  in 
quantity,  and  therefore  of  comparatively  little  influence  upon 
their  manuring  value.  Dry  blood  and  flesh  leave  about  4  per 
cent  of  ash,  while  wool,  hair,  and  horn  leave  only  1  or  2  per 
(yxt.  The  ash  of  flesh  and  fish  consists  almost  entirely  of  phos- 
phates, and  that  of  blood  in  great  part  of  common  salt.  This 
may  influence  their  respective  action  upon  plants — as  the  fact 
that  hair  contains  5  per  cent  of  sulphur  may  also  modify  the 
Action  of  this  substance  as  a  manure.     (See  p.  000.) 

SECTION  rV. COMPOSmON  OF  BONES  AND  THE  PITH  OF   HORNS,  AND 

THEIR  VALUE  AS  MANURES. 

1.  JBoTies,  while  they  resemble  hair  and  horn  in  being  dry, 


HORN,    FLINT   OR   PITH.  193 

differ  from  them  in  containing  a  large  quantity  of  earthy  matter, 
and  hence  they  introduce  a  new  agent  to  aii  their  effect  upon 
the  soil.     Thus,  the  bones  of  the  cow  consist  in  100  lb.  of — 


Phosphate  of  lime,  . 
Phosphate  of  magnesia, 
Soda  and  common  salt, 
Carbonate  of  lime,  . 
Pluoride  of  calcium, 
Gelatine  (the  substance  of  horn,) 


55J 

2 

2i 

31 

3 
334 

100. 


While  100  lb.  of  dry  bone-dust,  therefore,  add  to  the  soil  as 
much  organic  animal  matter  as  33  lb.  of  horn,  or  as  300  to  400 
lb.  of  blood  or  flesh,  they  add  at  the  same  time  two-thirds  of 
their  weight  of  inorganic  matter,  consisting  of  lime,  magnesia, 
soda,  common  salt,  and  phosphoric  acid  (in  the  phosphates) — 
all  of  which,  as  we  have  seen,  must  be  present  in  a  fertile  soil, 
since  the  plants  require  a  certain  supply  of  them  all  at  every 
period  of  their  growth.  These  substances,  like  the  inorganic 
matter  of  plants,  may  remain  in  the  soil,  and  may  exert  a  be- 
neficial action  upon  vegetation  after  alU  the  organic  or  gelati- 
nous matter  has  decayed  and  disappeared. 

2.  Horn  flints  or  piths,  resemble  bone  very  much  in  compo- 
sition. They  contain  a  little  more  animal  matter,  and  from 
their  softness  and  porosity  are  more  difficult  to  crush  in  the 
miU.  For  the  same  reason,  however,  they  decay  more  rapidly 
in  the  soil,  and  act  more  immediately  than  bones.  They  boil 
down,  however,  more  readily  than  bones,  and  are  therefore 
largely  used  for  making  the  size  used  in  stiffening  calicoes. 
For  this  purpose  they  are  sold  by  the  comb-makers  at  about 
£4r  a  ton. 

When  they  are  not  in  demand  for  this  purpose  they  may  be 
very  usefully  employed  as  a  manure. 

A  sample  of  the  pith,  as  it  is  sold  in  the  market,  gave  to 
Professor  Norton  in  my  laboratory — 
9 


194  .  PREPARATION   OF   DISSOLVED   BONES. 

Water,  Oost  at  212o,)           .        .        .  10.31 

Phosphates  of  lime  and  magnesia,         .  46.14 

.     Carbonate  of  lime,        ....  7.11 

Gelatine,  (organic  matter,)   .        .        .  35.84 

100. 

gECnON  V. PREPARATION  OF  DISSOLVED  BONES.      COMPARATIVE  EX« 

PERIMENTS    WITH    CRUSHED    AND    DISSOLVED    BONES.       WHY    THIS 
SOLUTION  MAKES  BONES  MORE  ACTIVE. 

For  the  purpose  of  bringing  bones  into  a  state  in  which  the 
substances  they  contain  can  be  more  readily  taken  up  by  the 
roots  of  plants,  and  at  the  same  time  more  uniformly  distri- 
buted through  the  soil,  the  method  has  been  adopted  of  dis- 
solving them  in  sulphuric  acid.  For  this  purpose,  the  bone-dust 
is  mixed  with  one-half  its  weight,  and  sometimes  with  its  own 
weight  of  sulphuric  acid  (the  oil  of  vitriol  of  the  shops,) 
previously  diluted  with  from  one  to  three  times  its  bulk  of 
water.  Considerable  effervescence  takes  place  at  first,  from 
the  action  of  the  acid  upon  the  carbonate  of  lime  in  the  bones; 
but,  after  two  or  three  days,  with  occasional  stirring,  the  bones 
are  entirely  dissolved  or  reduced.  The  solution  or  paste  may 
now  be  dried  up  with  charcoal  powder,  with  dried  or  charred 
peat,  with  sawdust,  or  with  fine  vegetable  soil,  and  applied 
with  the  hand  or  with  the  drill  to  the  turnip  crop  ;  or  it  may 
be  diluted  with  50  times  its  bulk  of  water,  and  let  off  into  the 
drills  with  a  water-cart.  Applied  either  way,  the  effect  is 
much  more  striking  than  when  the  same  weight  of  bone-dust  is 
applied  in  the  ordinary  form.    Thus — 

a.  At  Gordon  Castle  (Mr.  Bell)  the  following  results  were 
obtained  : — 

Manore  per  Imperial  Ao«.  Cost.  'SeTHyS" 

3  cwt.  guano,  1  17     0    (      9.25)  11-2     .. 

16  bushels  bones,  1  16    0    (     9.00)  11 


EXPERIMKNTS   WITH   DISSOLVED   BONES.  195 

Manure  per  Imperial  Acre.  Cost.  ^ilTny^^S!'"' 

2  bushels  bones,  ) 

83  lb.  sulplmric  acid,  [•        £0  11     6    ($2.88)  12-2     .. 

400  gallons  water,  ) 

8  bushels  bones,  j 

83  1b.    sulphuric    acid—  [•  1     5     0    (  6.25)  11 

sown  with  the  hand.  ) 

The  largest  produce  was  here  obtained,  when  the  dissolved 
bones  were  applied  with  a  water-cart;  and  at  a  cost  of  eleven 
shillings  per  acre. 

b.  Again,  on  the  farm  of  SherrifiFstoun  in  Morayshire,  (Mr. 
M'William,)  the  following  comparative  results  were  obtained  in 
1843  :— 

1.   Swedish  Turnips. 

-,  Cost  per  Produce  in  Bulbs  per 

^^^"'■^^  Acre.  Imperial  Acre. 

T5  lb.  (1-6  bushels)  bones,  ) 

46  lb.  acid,  [-£0     9     3     ($2.31)  17-5  tOM. 

400  gallons  water,  i 

The  same  with  200  gallons  [  o    9    3     C  2  31)  18*5 

water,  \  \    •    f 

440  lb.  (9-5  bushels)  bones,  [  i    4    9    f  6 19)  11 

28  lb.  of  acid,  f  \    •    f  •  • 

•  2.  Common  Turnips. 

ITO  lb.  (3-2  bushels)  bones,  ) 

92  lb.  acid,  >■   £0  IT     6    ($4.38)  16      tona 

400  gallons  water,  1 

16  bushels  bones,  ) 

46  lb.  acid,  |.      2     2     0    (  6.50)  13-5      . . 

10  gallons  water,  ) 

In  all  these  cases  the  smaller  quantity  of  bones,  when  di& 
solved  in  acid  and  applied  in  a  liquid  state,  gave  a  heavier 
return  of  bulbs  than  the  larger  quantity  when  drilled  in  dry 
Even  the  watering  of  the  large  quantity  of  bones  with  a  portion 
of  acid,  did  not  make  their  effect  on  the  crop  equal  to  that  of 
the  small  quantity  of  dissolved  bones. 


196 


INFLUENCE  OP  THE  SULPHURIC  ACID. 


Mr.  Hannam  obtained,  by  the  use  of  crushed  and  dissolved 
bones  upon  turnips,  the  following  results  : — 


Bones.   • 

Tons. 

cwts. 

16  bushels,  crushed,  gave 
2      ..      dissolved,  .. 
2 

10 
» 

11 

3  per  imperial  acre. 
12 
15 

4 

12 

11 

4 

14 

6 

4 

14 

11 

8 

13 

15 

8 

15 

2 

8 

16 

1 

We  can  explain  this  superior  action  of  dissolved  bones  by  the 
fact,  that  the  dissolving  separates  their  particles  completely  from 
each  other,  diffuses  them  more  completely  through  the  soil,  and 
presents  them  to  a  larger  surface  of  the  turnip  roots,  and  in  a 
state  in  which  they  can  be  more  readily  absorbed.  The  sul- 
phuric acid  also  may  have  some  effect,  since  we  know  that  sul- 
phur, in  some  form,  is  necessary  to  the  growth  of  all  our  crops. 
I  have  indeed  been  informed  of  a  case  at  Balcarras,  in  Fifeshire, 
where  diluted  sulphuric  acid  applied  alone  to  the  drills  produced 
an  excellent  crop  of  turnips  ;  and  of  another  in  Dumfriesshire, 
where  steeping  the  seed-corn  in  diluted  sulphuric  acid  added 
many  bushels  to  the  crop  of  barley. 

Though  the  immediate  effect  of  a  small  quantity  of  bones  on 
the  first  crop  is  made  so  much  greater  by  this  mode  of  applying 
them,  it  is  not  to  be  expected  that  the  effect  upon  the  after 
crops  should  be  as  beneficial  as  when  a  larger  quantity  of  bones 
is  applied  in  the  ordinary  method. 

SECTION  VI. COMPARATIVE  ACTION  OF  FLESH,  BLOOD,  HORN,  WOOLLEN 

RAGS,  AND  BONES. 


From  what  has  been  stated  in  the  preceding  sections  the 
reader  will  gather  these  general  conclusions — 

1.  That  animal  substances  which,  like  flesh  and  blood,  con 


GENERAL  CONCLUSIONS.  I9l 

tain  much  water,  decay  rapidly,  and  are  fitted  to  operate  mwie- 
diately  and  powerfully  upon  vegetation,  but  are  only  temporary 
or  evanescent  in  their  action.     (P.  192.) 

2.  That  when  dry,  as  in  horn,  hair,  and  wool,  they  decom- 
pose— and  consequently  act — more  slowly,  and  continue  to  ma- 
nifest an  influence,  it  may  be,  for  several  seasons. 

3.  That  bones  and  horn  flints  act  like  horn,  in  so  far  as  their 
animal  matter  is  concerned,  and,  like  it,  for  a  longer  or  shorter 
time,  according  as  they  have  been  more  or  less  finely  crushed; 
but  that  they  ameliorate  the  soil  by  their  earthy  matter  for  a 
still  longer  period — permanently  improving  the  condition,  and 
adding  to  the  natural  capabilities  of  the  land. 

4.  That  the  action  of  bones  may  be  rendered  more  imme- 
diate and  striking  by  bringing  them  into  a  minute  state  of  di- 
vision,— as  by  dissolving  them  in  diluted  sulphuric  acid,  or  by 
fermenting  them  in  a  mixture  of  moist  sand  or  soil — ^but  that, 
like  flesh  and  blood,  their  effect,  by  that  means,  is  likely  to  be 
rendered  less  permanent. 

SECTION   VII. — OF    THE     URINE     OF  ANIMALS,    AND    THE   MEANS   OF 
PRESERVING  AND  APPLYING  IT.      URATE.       SULPHATED  URINE,  &C. 

Practical  men  have  long  been  of  opinion  that  the  digestion 
of  food,  either  animal  or  vegetable, — its  passage  through  the 
bodies  of  animals — enriches  its  fertilising  power,  weight  for 
weight,  when  added  to  the  land.  Hence  in  causing  animals  to 
eat  up  as  much  of  the  vegetable  productions  of  the  farm  as 
possible — of  the  straw  and  turnip-tops,  for  example,  as  well  as 
of  the  grain  and  bulbs — it  is  supposed  that  not  only  is  so  much 
food  saved,  but  that  the  value  of  the  remainder  in  fertilising 
the  land  is  greatly  increased.  In  a  subsequent  section  we  shall 
see  how  far  theory  serves  to  throw  light  upon  these  opinions. 

Tlie  digested  animal  substances  usually  employed  as  manures 
are — the  urine  of  man,  of  the  cow,  and  of  the  sheep;  the  solid 
excrements  of  man  (nightsoil,)  of  the  horse,  the  cow,  the 


198  THE  TTBINE   OF  MAX. 

sheep,  and  the  pig,  and  the  droppings  of  pigeons  and  other 
birds.  The  liquid  manures  act  chiefly  through  the  saline  sub- 
stances which  they  hold  in  solution,  while  the  solid  manures 
contain  also  insoluble  matters  which  decay  slowly  in  the  soil, 
and  there  become  useful  only  after  a  time.  The  former,  there- 
fore, will  influence  vegetation  more  powerfully  at  first ;  the 
action  of  the  latter  will  be  less  evident,  but  will  continue  to  be 
sensible  for  a  much  longer  period  of  time. 

1.  Tht  urine  of  man. — Human  urine  consists,  in  1000  parts 
of— 

Water,            932 

Urea,  and  other  organic  matters  containing  nitrogen,  49 

Phosphates  of  ammonia,  soda,  lime,  and  magnesia,  .  6 

Sulphates  of  soda  and  ammonia,        ....  7 

Sal-ammoniac,  and  common  salt,      ....  6 

1000 
1000  lb.  of  urine,  therefore,  contain  68  lb.  of  dry  fertilising 
matter  of  the  richest  quality,  worth,  at  the  present  rate  of  selv- 
ing  artificial  manures  in  this  country,  at  least  10s.  a  cwt.  As 
each  full-grown  man  voids  about  1000  lb.  of  urine  in  a  year,  the 
national  waste  incurred  in  this  form  amounts,  at  the  above  va- 
luation, to  6s.  a  head.  And  if  5  tons  of  farmyard  manure  per 
acre,  added  year  by  year,  will  keep  a  farm  in  good  heart,  4 
cwt.  of  the  solid  matter  of  urine  would  probably  have  an  equal 
effect ;  or  the  urine  alone  discharged  into  the  rivers  by  a  popu- 
lation of  10,000  inhabitants  would  supply  manure  to  a  farm  of 
1500  acres,  and  would  yield  a  return  of  4500  quarters  of  corn, 
or  an  equivalent  produce  of  other  crops.  Mr.  Smith  of  Deans- 
ton  considered  the  urine  of  two  men  to  be  a  sufiBcient  manuring 
for  an  acre  of  land,  and  that  when  mixed  with  ashes,  it  would 
produce  a  fair  crop  of  turnips.* 

An  important  chemical  distinction  exists  between  the  urme 
of  man  and  that  of  the  cow,  the  horse,  and  the  sheep.  It  con- 
tains, as  is  shown  in  the  previous  page,  about  6  per  cent  of 

*  Report  of  Committee  on  Metropolitan  Sewerage. 


TJRINE    OF   THE    COW.  199 

phosphates,  while  these  compounds  are  entirely  absent  from  the 
arine  of  the  other  animals.  The  presence  of  the  phosphoric 
acid  contained  in  these  phosphates,  adds  very  much  to  the  ma- 
nuring value  of  human  urine. 

If  milk  or  lime  be  mixed  with  fermenting  human  urine,  this 
phosphoric  acid  is  precipitated  with  a  portion  of  the  animal 
matter.  Dr.  Stenhouse  found  a  precipitate  of  this  kind,  when 
dried  at  212°.  F.,  to  contain  40  per  cent  of  phosphoric  acid 
and  of  organic  matter,  including  about  1  per  cent  of  ammonia. 
By  the  use  of  this  method,  an  important  part  of  the  fertilising 
ingredients  of  human  urine  may  be  separated  in  a  solid  state. 
It  has  recently  been  adopted  with  some  success  for  the  purpose 
of  separating  the  fertilising  matters  contained  in  sewage 
water. 

2.  Pig's  urine. — The  urine  of  the  pig  resembles  that  of  man, 
in  containing  a  considerable  proportion  of  phosphoric  acid.  In 
this  respect  it  is  more  valuable  as  a  manure  than  those  of  the 
horse,  the  cow,  and  the  sheep. 

3.  The  urine  of  the  cow  is  said  to  contain  less  water  than 
that  of  man,  though  of  course  much  must  depend  upon  the 
kind  of  food  with  which  it  it  is  fed.  Considering,  then,  the 
large  quantity  of  liquid  manure  that  is  yielded  by  the  cow 
(1200  or  1500  gallons  a-year,)  we  may  safely  estimate  the 
solid  matter  given  off  by  a  healthy  animal  in  the  form  of  urine 
in  twelve  months,  at  about  1000  lb.  in  weight — worth,  if  it 
were  in  the  dry  state,  from  £4  to  £,b  sterling.  In  the  liquid 
state,  the  urine  of  one  cow,  collected  and  preserved  as  it  is  in 
Flanders,  is  valued  in  that  country  at  about  £2  a-year.  Any 
practical  farmer  may  calculate  for  himself,  therefore,  how  much 
real  wealth,  taking  it  even  at  the  Flemish  value,  is  lost  in  his 
own  farmyard — how  much  of  the  natural  means  of  reproduc- 
tive industry  passes  into  his  drains,  or  evaporates  into  the 
air. 

This  liquid  manure  is  very  valuable,  when  collected  in  tanks, 
for  watering  the  manure  and  compost  heaps,  and  thus  hastoj*. 


OONSTKUCIION   OF   LIQUID-MANURE  TANKS 

ing  their  decomposition.  It  may  also  be  sprinkled  directly 
upon  the  fields  of  grass  or  of  clover,  and  upon  the  young  corn, 
— or  the  young  green  crop  (turnips,  &c.)  may  be  watered  with 
it,  with  the  best  eflfects.  It  must,  however,  be  permitted  to 
stand  till  fermentation  commences,  and  must  afterwards  be 
diluted  with  a  considerable  quantity  of  water,  before  it  will  be 
in  the  best  condition  for  laying  upon  the  land.  This  dilution, 
indeed,  where  the  receiving  tanks  are  large  enough,  should  be 
made  at  an  earlier  period,  for  it  has  been  found  that,  when  un- 
mixed with  water,  cows'  urine,  which  is  six  weeks  old,  contains 
only  one-sixth  part  of  the  ammonia  retained  by  the  same  urine 
when  it  has  been  previously  diluted  with  an  equal  bulk  of 
water.     Sulphuric  acid  may  also  be  added  to  fix  the  ammonia.* 

4.  Of  the  construction  of  liquid-manure  tanks. — There  are  four 
practical  points  which  are  worthy  of  attention  in  the  construc- 
tion of  tanks  for  liquid  manure. 

a.  They  ought  to  be  well  puddled  with  clay  behind  the  stone 
or  brick  work,  to  prevent  any  loss  or  escape  of  the  liquid. 

h.  They  ought  to  be  covered  over,  and  the  closer  the  better. 
In  Germany  they  are  usually  vaulted.  From  close  tanks  the 
sun,  rain,  and  air,  are  in  a  great  measure  excluded,  and  the  fer- 
mentation is  slower,  and  the  loss  of  ammonia  in  consequence 
considerably  less. 

c.  They  should  be  divided  by  a  wall,  into  at  least  two  com- 
partments, capable  of  holding  each  a  two  or  three  months'  sup- 
ply. When  the  first  of  these  is  full,  the  stream  is  turned  into 
the  second,  and  by  the  time  it  is  also  full,  the  contents  of  the 
first  are  ripe,  or  in  a  fit  state  for  putting  upon  the  land.    The 

*  To  saturate  and  fix  the  whole  of  the  ammonia  capable  of  being  fonned 
in  the  urine  of  a  single  cow  of  average  size,  would  require  about  VOO  lb.  of 
the  common  strong  sulphuric  acid  of  the  shops,  or  nearly  60  lb.  a  month, 
costing  9s.  One- third  or  one-fourth  of  this  quantity,  however,  added  to  the 
liquid-manure  tank,  would  be  sufficient  to  prevent  any  very  sensible  loss. 
Mr.  Kinninmonth  found  750  gallons  of  cows'  urine  so  treated,  with  about 
15  lb.  of  acid,  equal  in  increasing  the  produce  of  hay  to  2^  cwt.  of  guan(^ 
or  1  cwt.  of  nitrate  of  soda. 


URATE  AND  SULPHATED  URINE.  201 

liquid  ought  always  to  be  in  a  state  of  fermentation  before  it  is 
applied  either  to  grass  or  to  any  other  crop.  This  double  tank 
also  enables  the  farmer  to  collect  and  preserve  his  liquid  during 
the  three  months  of  winter,  when  it  cannot  be  applied,  and  to 
have  a  large  supply  in  a  fit  state  for  putting  on  when  the  young 
grass  or  corn  begins  to  shoot. 

The  liquid  as  it  comes  from  the  cattle  ought  to  be  mixed  in 
the  tank  with  at  least  its  own  bulk  of  water.  By  this  means  a 
considerable  loss  of  ammonia  is  prevented  which  would  other- 
wise escape  from  the  urine  during  fermentation  ;  and  it  is  pre- 
vented from  burning  the  grass,  which  in  very  dry  seasons  it  is 
apt  to  do  when  put  on  without  dilution.  This  necessarily 
involves  larger  cisterns,  and  more  labor  in  carrying  out  the 
liquid  ;  but  experience  seems  to  say  that  the  additional  profit 
exceeds  considerably  the  additional  expense. 

5.  Urate. — Among  other  methods  of  obtaining  the  virtues  of 
animal  urine  in  a  concentrated  form,  burnt  gypsum  is  mixed 
with  it  in  the  state  of  powder  in  the  proportion  of  10  lb.  to 
every  1  gallons,  allowing  the  mixture,  occasionally  stirred,  to 
stand  some  time,  pouring  off  the  liquid,  and  drying  the  gypsum. 
This  is  sold  by  manure  manufacturers  under  the  name  of  %rate. 
It  never  can  possess,  however,  the  virtues  of  the  urine,  since  it 
does  not  contain  the  soluble  saline  substances,  which  the  gypsum 
does  not  carry  down  with  it.  Except  the  gypsum,  indeed,  100 
lb.  of  urate  contain  no  greater  weight  of  saline  and  organic 
matter  than  ten  gallons  of  urine.  If  it  be  true,  then,  as  the 
manufacturers  state,  that  3  or  4  cwt.  of  urate  are  sufficient 
manure  for  an  acre,  the  practical  farmer  will,  I  hope,  draw  the 
conclusion, — not  that  it  is  well  worth  while  to  venture  his  money 
in  buying  this  urate,  and  trying  it  upon  his  land,  but  that  a  far 
more  promising  adventure  will  be  to  go  to  some  expense  in  sav- 
ing his  own  liquid  manure,  and  after  mixing  it,  if  he  think 
proper,  with  the  burned  gypsum,  to  lay  it  abundantly  upon  all 
his  fields. 

6.  Sulphaled  urine. — A  better  method  than  that  of  using 

9*  • 


202  AMMONIACO-MAGNESIAK   PHOSPHATE. 

gypsum  has  been  lately  adopted  by  several  manure  manufac- 
turers. They  mix  as  much  sulphuric  acid  with  the  urine  as  is 
sufficient  to  combine  with  and  fix  the  whole  of  the  ammonia 
which  may  be  produced  during  the  decomposition  of  the  urine. 
The  mixture  is  then  evaporated  to  dryness,  and  is  sold  and 
applied  to  the  land  in  the  state  of  a  dry  powder. 

This  sulphated  urine,  containing  as  it  does  all  the  saline  sub- 
stance of  the  liquid  urine,  with  the  addition  of  sulphuric  acid, 
ought  to  prove  a  most  valuable  manure.  If  prepared  from 
human  urine,  it  will  promote  the  growth  of  nearly  all  crops  ; 
but,  from  the  sulphuric  acid  it  contains,  it  may  exercise  a  special 
influence  on  beans,  peas,  and  clovers.  As  a  top-dressing  it  may 
be  applied  alone  ;  but  when  used  for  root-crops,  it  ought  to  be 
mixed  with  and  to  take  the  place  of  not  more  than  one-half  of 
the  farmyard  manure  usually  applied.  Used  in  this  way,  at  a 
cost  of  £2  an  acre,  Mr.  Finnic  of  Swanston  obtained,  in  1843, 
four  tons  of  turnips  per  imperial  acre  more  than  from  an  equal 
cost  of  guano. 

As  a  top-dressing  for  wheat,  and  probably  also  for  other  corn 
crops,  this  sulphated  urine  may  be  advantageously  mixed  with 
an  equal  weight  of  sulphate  of  soda  or  of  common  salt,  with  at 
least  as  much  wood  ashes,  if  they  can  be  had,  and  with  half  its 
weight  of  dissolved  bones.  The  soda  salts  are  especially  desir- 
able where  the  land  lies  remote  from  the  sea. 

1.  Ammoniaco-magnesian  phosphate. — Boussingault  fixes  the 
ammonia  a^d  phosphoric  acid  of  human  urine  by  adding  to  it, 
after  it  has  acquired  an  ammoniacal  odor,  a  solution  of  sul- 
phate or  muriate  of  magnesia,  when  the  double  phosphate  ot 
magnesia  and  ammonia  falls  to  the  bottom  of  the  liquid. 
About  T  lb.  of  this  salt  are  obtained  from  100  lb.  of  ui'ine ; 
and  it  has  been  ascertained  to  possess  powerful  fertilising  pro- 
perties.* 

*  In  reference  to  liquid  manures,  I  strongly  recommend  to  my  readers, 
the  "Minutes  of  Information  collected  on  the  Practical  Application  of 
Sewer  "Water,  and  Town  Manures,  ;o  Agricultural  Purposes,"  pviblisbed  ^7 
the  General  Board  of  Health. 


CHAPTER  XV. 

Animal  manures  contin-aed. — Solid  excretions  or  droppings  of  animals.— 
Niglitsoil. — Poudrette. — Taffb. — Cow,  horse,  and  pigs'  dung. — Droppings 
of  birds. — Pigeons'  dung. — Guano. — African  and  American  varieties. — 
Their  composition,  and  fertilising  values. — Their  durability. — Adultera- 
tion o^  how  to  test  or  select  a  good  sample,  quantity  imported,  and  va- 
lue to  the  nation. 

The  solid  excretions  of  animals  are  not  less  valuable  as  ma- 
nures than  their  urines,  and  in  almost  every  country  are  much 
more  generally  employed. 

SECTION   I. — OF  NIGHTSOIL,  POUDRETTE,  AND   TAFFO  ;   AND   OF   COW, 
HORSE,    AND    PIGS'   DUNG. 

1.  NightsoU  is  probably  the  most  valuable  of  all  the  solid 
animal  manures.  It  varies  in  richness  with  the  food  of  the  in- 
habitants of  each  district,* — chiefly  with  the  quantity  of  ani- 
mal food  they  consume, — but  when  dry,  few  other  solid  manures, 
weight  for  weight,  can  be  compared  with  it  in  general  efl&cacy. 
It  contains  much  soluble  and  saline  matter,  and  as  it  is  made 
up  from  the  constituents  of  the  food  we  eat,  of  course  it  con- 
tains most  of  those  elementary  substances  which  are  necessary 
to  the  growth  of  the  plants  on  which  we  principally  live. 

2.  Poudrette. — Attempts  have  been  made  to  dry  nightsoil  so 

♦  This  is  said  to  be  so  well  known  in  some  of  the  towns  in  the  centre  of 
Europe,  where  a  mixed  population  of  Protestants  and  Roman  Catholics  live 
together,  that  the  neighboring  farmers  give  a  larger  price  for  the  house- 
dung  of  the  Pro  .estant  families.  In  Persia,  the  nightsoil  of  the  Russian 
families  is,  ibr  a  similar  reason,  preferred  to  that  of  the  less  flesh-eating 
M&hometans. 


204  cow,    HORSE   AND   PIGS'   DUNG 

as  to  render  it  more  portable, — to  destroy  its  unpleasant  smell, 
so  as  to  reconcile  practical  men  to  a  more  general  use  of  it, — 
and,  by  certain  chemical  additions,  to  prevent  the  waste  of  am- 
monia and  other  volatile  substances,  which  are  apt  to  escape 
and  be  lost  when  this  and  other  powerful  animal  manures  begin 
to  putrefy.  In  Paris,  Berlin,  and  other  large  cities,  the  night- 
soil,  dried  first  in  the  air  with  or  without  a  mixture  of  gypsum 
or  lime,  then  upon  drying-plates,  and  finally  in  stoves,  is  sold 
under  the  name  of  poudrette,  and  is  extensively  exported  in 
casks  to  various  parts  of  the  country.  It  is  said  to  be  equal 
in  pflBcacy  to  30  times  its  bulk  of  horse  or  street  manure,  and 
is  applied  at  the  rate  of  from  15  to  35  bushels  an  acre. 

In  London,  also,  nightsoil  is  dried  with  various  admixtures; 
and  in  some  of  our  other  large  towns  an  animalised  charcoal  is 
prepared  by  mixing  and  drying  nightsoil  with  gypsum  and  or- 
dinary wood  charcoal,  in  fine  powder.  Charred  peat  would 
answer  well  for  such  a  purpose. 

Few  simple  and  easily  attainable  substances  would  make  a 
better  compost  with  nightsoil,  and  more  thoroughly  preserve 
its  virtues,  than  half-dried  peat,  saw-dust,  or  rich  vegetable 
soil,  mixed  with  more  or  less  marl  or  gypsum.  It  is  impossible 
to  estimate  the  proportion  of  waste  which  this  valuable  manure 
undergoes  by  being  allowed  to  ferment,  without  mixture,  in  the 
open  air. 

3.  Taffo. — In  China  nightsoil  is  kneaded  into  cakes  with 
clay,  which  are  dried  in  the  air,  and,  under  the  name  of  taffo, 
form  an  important  article  of  export  from  all  the  large  cities  of 
the  empire.  In  Persia  it  is  dried  in  the  sun  and  powdered. 
Mixed  with  twice  its  bulk  of  dry  soil,  it  is  then  used  for  raising 
the  finest  melons. 

4.  Cow,  horse,  and  pigs^  dung.  So  much  of  the  saline  and 
soluble  organic  matters  in  the  excretions  of  the  cow  pass  off  in 
the  liquid  form,  that  its  dung  is  correctly  called  cold,  since  it 
does  not  readily  heat  and  run  into  fermentation.  Mixed  with 
other  manures,  however,  or  well  diffused  through  the  soil,  it 


DROPPINGS   OF   BIRDS.  ^  JD 

aids  materially  iu  promoting  vegetation.  The  horse  being  fed 
generally  on  less  liquid  food,  and  discharging  less  urine,  yields 
a  hotter  and  richer  duag,  which  is  admirably  fitted  for  bringing 
substances  into  a  state  of  fermentation,  but  answers  best  for 
the  land  when  mixed  with  other  varieties  of  manure.  The 
dung  of  the  pig  is  soft  and  cold  like  that  of  the  cow,  contain- 
ing, like  it,  at  least  15  per  cent  of  water.  As  this  animal  lives 
on  more  varied  food  than  any  other  which  is  reared  for  the  use 
of  man,  the  manure  obtained  from  it  is  also  very  variable  in 
quality.  Applied  alone,  as  a  manure  to  roots,  it  is  said  to  give 
them  an  unpleasant  taste,  and  to  injure  the  flavor  even  of  the 
tobacco  plant.  It  answers  well  for  hemp  and  for  hops ;  but 
when  mixed  with  other  manures,  it  may  be  applied  to  any  crop. 
In  some  districts  pigs'  dung  is  considered  one  of  the  richest 
and  most  valuable  that  can  be  applied  to  the  land.  But  the 
most  generally  useful  manure  is  obtained  by  mixing  all  these 
varieties  together,  as  is  usually  done  in  the  manure-heaps  of 
«ir  larger  farmers. 

SECTION    II. DROPPINGS    OF    BIRDS.        PIGEONS'    DUNG    AND    GUANO. 

AFRICAN  AND  AMERICAN  VARIETIES THEIR  COMPOSITION  AND  FER- 
TILISING EFFECTS, 

1.  Pigeons'  dung. — The  dung  of  nearly  all  birds  is  distin- 
guished by  eminent  fertilising  properties.  Some  varieties  are 
stronger  than  others,  or  more  immediate  in  their  action,  and 
all  are  improved  for  the  use  of  the  farmer  by  being  some  time 
kept,  either  alone  or  in  compost.  In  Flanders  the  manure  of 
one  hundred  pigeons  is  considered  to  be  worth  20s.  a-year  for 
agricultural  purposes.  In  Catalonia,  Arragon,  and  some  other 
parts  of  Spain,  pigeons'  dung  is  sold  as  high  as  4d.  a  pound, 
for  applying,  when  mixed  with  water,  to  flower-roots,  melons, 
tomatos,  and  other  plants.* 

*  The  estimation  in  which  it  was  held  iu  ancient  Palestine  may  be  in* 
ferred  from  the  statement,  that,  during  a  siego  of  Samaria,  tho  fourth  part 


S06  6UAN0   AND   FARMYARD  DUNG. 

The  dung  of  birds  possesses  the  united  virtues  of  both  the 
liquid  and  solid  excretions  of  other  animals.  It  contains  every 
part  of  the  food  of  the  bird,  with  the  exception  of  what  is  abso- 
lutely necessary  for  the  support  and  for  the  right  discharge  of  the 
functions  of  its  own  body.  It  is  thus  fitted  to  return  to  the 
plant  a  greater  number  of  those  substances  on  which  plants  live, 
than  either  the  solid  or  the  fluid  excrements  of  other  animals  ; 
in  other  words,  to  be  more  propitious  to  vegetable  growth. 

2.  Guano  is  the  name  given  by  the  natives  of  Peru  to  the 
dung  of  sea-fowl,  which  in  former  periods  used  to  be  deposited 
in  vast  quantities  on  the  rocky  shores  and  isles  of  the  Peruvian 
coast.  The  numerous  shipping  of  modern  times  has  disturbed 
and  driven  away  many  of  the  sea-fowl,  so  that  much  less  of 
their  recent  droppings  is  now  preserved  or  collected.  Ancient 
heaps  of  it,  however,  mixed  with  feathers  and  fragments  of 
bone,  still  exist  in  many  places,  more  or  less  covered  up  with 
drifted  sand,  and  also  more  or  "less  decomposed.  These  are  now 
largely  excavated,  especially  on  the  Chincha  islands,  for  expor- 
tation, not  only  to  different  parts  of  the  coast  of  Peru, — as 
seems  to  have  been  the  case  from  the  most  remote  periods, — but 
also  to  Europe,  and  especially  to  England.  It  is  at  present  sold 
in  this  country  at  a  price  which  varies  from  i28  to  £11  a  ton. 

Guano  was  also  imported,  for  a  few  years,  (1843  to  184*1,) 
in  large  quantities  from  the  island  of  Ichaboe,  and  from  other 
places  on  the  west  coast  of  Africa.  The  quality  of  the  African 
was  not  equal,  however,  to  that  of  the  guano  brought  from 
Peru.  It  contained  more  water,  and  was  in  a  more  advanced 
Btage  of  decomposition.  The  known  sources  of  supply  from  this 
quarter  are  now  nearly  exhausted  ;  and  with  the  exception  per- 
haps of  a  little  from  Saldanha  Bay,  there  is  none  of  it  now  in 

of  a  cab  of  doves'  dung  was  sold  for  5  pieces  of  silver. — 2  Bangs  vi.  25. 
I  may  state,  however,  that  what  is  here  translated  doves'  dung,  was  con- 
Bidered  by  Linnaeus  to  mean  the  bulbous  root  of  the  Ornithogallum  umbeU 
latum,  still  eaten  in  Palestine,  and  forming  part  of  the  food  of  some  of  the 
Iribes  of  Hottentots  at  the  Cape  of  Good  Hope. 


FERTILISING   EFFECT   OF   GUANO, 


207 


tuc  market.  Its  price  varied  with  the  quality,  from  £S  to  £8 
a  tou. 

Gu«ino  is  capable  of  entirely  replacing  farmyard  dung, — that 
is  to  suy,  turnips  and  potatoes  may  be  manured  successfully  with 
guano  alone.  It  may  be  used  either  as  a  top-dressing  to  the 
young  corn  and  grass  ;  or  it  may  be  put  in  with  the  turnip-seed, 
or  with  the  potato  cuttings,  being  previously  mixed  with  a  quan- 
tity of  fine  dry  soil,  charcoal  powder  or  gypsum.  It  may  also 
be  mixed  with  water,  and  used  as  a  liquid  manure.  It  is 
applied  in  various  proportions,  from  one  to  three,  four,  or  five 
hundred  weights  per  acre.  Three  cwt.  of  guano,  without  other 
manure,  gave  Mr.  Fleming  of  Barochan  18^  tons  of  potatoes 
per  acre  ;  and  6  cwt.,  with  20  bushels  of  wood  ashes,  gave  him 
32  tons  of  yellow  turnips. 

The  application  o^  guano  to  the  sugar  cane  has  largely 
increased  the  produce  of  sugar,  both  in  the  British  West  India 
Islands  and  in  the  Mauritius. 

When  applied  in  too  large  a  quantity,  the  effect  both  upou 
the  turnip  and  upon  the  after  corn-crop  is  of  a  very  hurtful 
kind.  This  is  very  strikingly  shown  by  the  following  results 
of  an  experiment  made  in  Ross-shire  (in  1843  and  1844)  with 
4,  8,  and  16  cwt.  respectively  to  the  Scotch  acre  : — 


Quantity  of 
Guano. 

Effect  on  th*  Turnip  Crop. 

Ou  tho  after  crop  of 
Wheat. 

4  cwt. 
8     .. 

( 
16     .,      J 

Good  turnips,  18  tons. 
Very  indiflerene,  14  tons. 
Grew    up    woi.derfully, 
looked    beautiful,     but 
there  was  Utile  bJb. 
Produce  10  tons. 

Good  Wheat. 
Inferior. 

Stubble  black,    grain 
•<  dark,  and   not  larger 
)  than  small  rice. 

3.  The  fertilising  effects  of  guano  depend  mainly  upon  the 
quantity  of  ammonia  which  already  exists  in  it,  or  which  may 
be  formed  in  it  by  its  further  decomposition,  and  upon  the  pro- 


208 


COMPOSITION   OF  GUANOS, 


portion  of  phosphates  which  are  present  in  it  Of  these  tho 
former  is  the  more  valuable  ingredient  of  the  two — that  is  to 
say,  it  would  cost  the  farmer  most  money  to  buy  it  in  a  sepa- 
rate state,  at  its  present  price.  The  phosphates,  in  like  man- 
ner, would  cost  more  to  buy  in  the  shape  of  bones  or  of  sugar- 
refiners'  refuse,  (animal  charcoal,)  than  any  of  the  other 
ingredients  which  the  guano  contains — the  ammoniacal  matter 
excepted. 

4.  Composition. — The  following  table  exhibits  the  composi- 
tion of  four  samples  of  guano,  two  from  the  South  American 
and  two  from  the  African  coast.  These  analyses  do  not  enter 
much  into  details,  but  they  are  sufficient  for  ordinary  purposes 
— ViS  guides,  that  is,  to  the  practical  man. 


"Water,      - 

Organic  matter  con-  ) 

taining  ammonia. 
Common     salt    and 

sulphate  of  soda,    J 
Carbonate  of  lime, 
Phosphates  of  lime  ) 

and  magnesia,         C 
Silicioua    matter   or  | 

eand,                      j 

South  American. 

Africaw. 

Peruvian. 

Bolivian. 

Ichaboe. 

Saldanha 
Bay. 

13.09 
53.17 

4.63 

4.18 

23.54 

1.39 

6.91 
55.52 

6.31 

3.87 

25.68 

1.71 

16.71 
46.61 

12.92 

0.27 

22.40 

0.52 

18.35 
22.14 

5.78 

1.49 

50.22 

2.02 

100. 

100. 

99.43 

100. 

These  analyses  are  not  to  be  considered  as  doing  more  than 
gmerally  representing  the  difference  between  the  African  and 
American  guanos.  The  several  cargoes,  both  of  African  and 
of  American,  which  used  to  arrive  in  this  country,  differed  much 
among  themselves.  As  I  have  already  stated,  the  importation 
of  African  guano  has  now  almost  entirely  ceased. 


PERMANENCE   OF   THEIR  ACTION.  209 

It  is  one  of  the  valuable  qualities  of  guano,  that  it  contains 
a  mixture  of  so  many  of  these  substances  on  which  plants  live. 
The  only  ingredient  in  which  it  is  manifestly  defective  is  potash 
— of  which  it  usually  contains  less  than  1  per  cent ;  and  hence 
an  admixture  of  wood  ashes,  and  especially  of  leached  or  washed 
wood  ashes,  would  be  likely  to  improve  its  action  upon  the 
crops,  in  such  soils  as  do  not  naturally  abound  in  potash. 

5.  Loios  Islands  guano,  which  is  at  this  moment  attracting 
so  much  of  the  attention  of  politicians,  is  said  to  be  the  pro- 
duce of  the  seal  or  sea-wolf,  and  to  be  from  25  to  33  per  cent 
less  valuable  than  the  guano  of  the  Chincha  islands. 

6.  British  guano. — The  successful  employment  of  foreign 
guano  has  caused  the  droppings  of  pigeons,  sea-fowls,  and  bats, 
to  be  sought  for  in  the  caves  along  our  east  and  west  coasts,  and 
in  our  western  islands.  I  have  examined  several  samples  from 
both  coasts  ;  but  though  they  may  prove  valuable  manures  in 
the  immediate  neighborhood  where  they  are  found,  they  are  not 
rich  enough  to  pay  the  cost  of  collection  and  transport  to  any 
considerable  distance. 

1.  Is  guano  permanent  in  its  action  ? — ^This  is  a  question  which 
the  practical  man  naturally  asks  when  he  is  about  to  employ  it 
to  a  large  extent.  Experience  seems  to  show  that  its  beneficial 
action  extends  to  at  least  two  crops,  when  it  is  applied  in  proper 
quantity.  Theory  also  indicates,  that  though  the  action  of  the 
ammoniacal  salts  may  be  more  or  less  exhausted  in  a  single  sea- 
son, yet  that  the  effect  of  the  phosphates  and  other  saline  sub- 
stances it  contains — which  is  very  important — will  continue 
beyond  one  year.  But  the  kind  and  quality  of  the  guano  will 
materially  affect  the  length  of  its  action. 

In  general,  however,  it  may  be  said,  that  as  guano  resembles 
bones  very  much  in  its  composition,  and  as  bones  are  known  to 
benefit  the  crops  in  an  entire  rotation,  so  ought  guano  also. 
The  chief  difference  between  bones  and  guano  is  this — that  the 
guano  contains  ammonia  ready  formed,  or  forming,  so  to  speak 
— while  the  bones  contain  gelatine,  which  forms  ammonia  only 


210  ADULTERATION    OF   GUANO. 

after  it  has  fermented.  The  ammoniacal  part  of  the  one,  there- 
fore, will  act  early,  of  the  other  after  a  longer  period — while 
the  permanent  effects  of  the  remaining  ingredients  of  both  will 
be  very  much  alike  if  they  are  laid  on  in  nearly  the  same 
proportions. 

SECTION  III. ADULTERATIONS    OF   GUANO HOW   TO    SELECT   A   SAM- 
PLE   OF   GOOD   QUALITY NATIONAL  VALUE    OF   THIS   MANURE. 

1.  Adulterations  of  guano. — ^In  consequence  of  the  high  price 
of  guano,  the  great  demand  for  it,  and  the  ease  with  which  the 
unwary  farmer  may  be  imposed  upon,  guano  is  adulterated  with 
various  substances,  and  to  a  great  extent.  Impositions  even 
have  been  practised  by  selling  as  genuine  guano  artificial  mix- 
tures, made  to  look  so  like  guano  that  the  practical  man  in 
remote  districts  is  unable  to  detect  it.  A  sample  of  such  pre- 
tended guano,  which  had  been  sold  in  the  neighborhood  of  Wig- 
town, and  had  been  found  to  produce  no  effect  upon  the  crops, 
when  examined  in  my  laboratory,  was  found  to  contain,  in  the 
state  in  which  it  was  sold,  more  than  half  its  weight  of  gypsum — 
the  rest  being  peat  or  coal  ashes,  with  a  little  common  salt,  sul- 
phate of  ammonia,  and  either  dried  urine  or  the  refuse  of  the 
glue  manufactories,  to  give  it  a  smell.  I  could  not  satisfy 
myself  that  it  contained  a  particle  of  real  guano.  Burnt  earth 
and  brick-dust  are  now  prepared  of  various  shades,  and  in  fine 
powder,  in  special  manufactories,  for  the  purpose  of  mixing  with 
guano  and  with  artificial  manures.  These  facts  show  how 
important  it  is  that  the  farmer  should  possess  some  means  of 
readily,  and  at  a  cheap  rate,  testing  the  costly  manures  he 
employs.* 

*  "  Four  vessels  receiitly  tailed  hence  for  guano  stations  ballasted  with 
gypsum,  or  plaster  of  Paris.  This  substance  is  intended  for  admixture  with 
guano ;  and  will  enable  the  pnrties  to  deliver  from  the  vessel  a  nice-looking 
and  hght-colored  article.  Parties  purchasing  guano  are  very  desirous  of 
Laving  it  delivered  from  the  vessel,  as  they  believe  they  obtain  it  pure.    Tbo 


HOW  TO   SELECT  A  GOOD   GUANO.  211 

2,  In  selecting  a  good  guano,  the  following  simple  observations 
will  aid  the  practical  man. 

a.  The  drier  the  better — there  is  less  water  to  pay  for  and  to 
transport. 

I.  The  lighter  the  color,  the  better  also.  It  is  the  less  com- 
pletely decomposed. 

c.  If  it  has  not  a  strong  ammoniacal  smell,  it  ought  to  give 
off  such  a  smell  when  a  spoonful  of  it  is  mixed  with  a  spoonful 
of  slaked  lime  in  a  wine  glass. 

d.  When  put  into  a  tumbler  with  water,  stirred  well  about, 
and  the  water  and  fine  matter  poured  off,  it  ought  to  leave  little 
sand  or  stones. 

c.  When  heated  to  redness  in  the  air  till  all  the  animal  mat- 
ter is  burned  away,  the  ash  should  nearly  all  dissolve  in  dilute 
muriatic  acid.  The  insoluble  matter  is  useless  sand  or  earthy 
adulterations. 

/.  In  looking  at  the  numbers  in  a  published  analysis  of  a 
Peruvian  guano,  those  representing  the  water  should  be  small ; 
the  organic  matter  containing  ammonia  should  approach  to  50 
or  60  per  cent ;  the  phosphates  should  not  much  exceed  20  per 
cent ;  and  the  common  salt  and  sulphate  of  soda  ought  not  to 
form  much  more  than  5  or  6  per  cent  of  the  weight  of  the  guano. 
In  Saldanha  Bay  guano  the  proportion  of  phosphates  was  much 
greater,  and  of  organic  matter  less. 

3.  The  national  value  of  guano,  and  the  consequent  import- 
ance of  preventing  adulteration  as  far  as  possible,  may  be  judged 
of  from  three  important  facts. 

a.  From  the  amount  of  the  importation  of  it  into  this  coun« 
try,  which,  during  the  last  ten  years,  has  been  as  follows  : — 

kvoiite  materral  'bi  the  adulteration  of  guano,  at  the  present  moment,  is 
amber,  which  is  brought  from  Anglesea  in  large  quantities.  The  rate  of 
admixture,  we  are  mformed,  is  about  15  cwt.  of  umber  to  about  5  cwt.  of 
Feiuvian  guano,  from  which  an  excellent-looking  article,  called  African 
guano,  is  manufactured." — Liverpool  paper. 


212 


YEARLY  IMPORTATION   OP  GUANO. 


Yeara 

Tons. 

Years. 

Tom. 

1841, 

2,881 

1847, 

82,000 

1842, 

20,398 

1848, 

71,414 

1843, 

3,002 

1849, 

83,438 

1844, 

104,351 

1850, 

.   116,925 

1845, 

283,300 

1861, 

.   245,016 

1846, 

89,203 

h.  That  the  quantity  imported  in  1851  would  sell  for  upwards 
of  two  millions  sterling,  and  with  good  management  ought  to 
produce  two  or  three  times  its  own  value  in  grain  or  other  vege- 
table food.  In  other  words,  such  a  yearly  supply  of  guano  is 
equal  to  the  importation  of  foreign  grain  and  other  produce  to 
the  value  of  from  four  to  six  millions  sterling. 

c.  It  also  serves  as  a  stimulus,  while  it  supplies  one  of  the 
requisites,  to  the  general  introduction  of  improved  methods  of 
agricultural  practice. 


CHAPTER  XYI. 

Relative  theoretical  values  of  different  animal  manures. — Chemical  distino 
tion  or  difference  between  animal  and  vegetable  manures. — Cause  of  this 
difference. — Effects  of  respiration. — Coldness  of  the  droppings  of  the  cow, 
and  poorness  of  the  manure  from  growing  stock. — Improvement  of  the 
land  by  eating  off  with  sheep. 

SECTION  I. OF  THE  RELATIVE  THEORETICAL  VALUES  OF  THE  DIFFER- 
ENT  ANIMAL   MANURES. 

The  fertilising  power  of  animal  manures,  in  general,  is  dO' 
pendent,  like  that  of  the  soil  itself,  upon  the  happy  admixture 
they  contain  of  a  great  number  of  those  substances  which  are 
required  by  all  plants  in  the  universal  vegetation  of  the  globe. 
Nothing  they  contain,  therefore,  is  without  its  share  of  influ- 
ence upon  their  general  effects  ;  yet  the  amount  of  nitrogen 
present  in  each  affords  one  of  the  readiest  and  most  simple 
tests  by  which  their  relative  agricultural  values,  compared 
mth  those  of  vegetable  matters,  and  vdth  each  other,  can  be 
pretty  nearly  estimated. 

In  reference  to  their  relative  quantities  of  nitrogen,  there- 
fore, they  have  been  arranged  in  the  following  order — the  num- 
ber opposite  to  each  representing  the  weight  in  pounds,  which 
is  equivalent  to,  or  would  produce  the  same  sensible  effect  upon 
the  soil  as  100  lb.  of  farmyard  manure: — 


Farmyard  manure, 

Sohd  excrements  of  the  cow, 

horse, 

Liquid  excrements  of  the  cow, 

horse, 

Mixed  excrements  of  the  cow, 

horse, 

— ■ sheep, 

pig, 


100 
125 
73 
91 
16 
98 
64 
36 
64 


S14 


KELATIVE  VALUES  OF  ANIMAL  MANURES. 


Dry  flesh, 

8 

Pigeons'  dung,      . 

6 

Flemish  hquid  manure, 

200 

Liqviid  blood, 

16 

Dry  blood. 

4 

leathers, 

3 

Cow  hair, 

8 

Horn  shavings     . 

3 

Dry  woollen  rags, 

2i 

It  is  probable  that  the  numbers  in  this  table  do  not  err  very 
widely  from  the  true  relative  values  of  these  different  manures, 
in  so  far  as  the  organic  matter  they  severally  contain  is  con- 
cerned.    The  reader  will  bear  in  mind,  however — 

1.  That  the  most  powerful  substances  in  this  table,  woollen 
rags  for  example — 2^  lb.  of  which  are  equal  in  virtue  to  100 
lb.  of  farmyard  manure — may  yet  show  less  immediate  and  sen- 
sible effect  upon  the  crop  than  an  equal  weight  of  sheep's 
dung,  or  even  of  urine.  Such  dry  substances,  as  I  have  said, 
are  long  in  dissolving  and  decomposing,  and  continue  to  evolve 
fertilising  matter,  after  the  softer  and  more  fluid  manures  have 
spent  their  force.  Thus,  while  farmyard  manure  or  rape-dust 
will  immediately  hasten  the  growth  of  turnips,  woollen  rags 
will  come  into  operation  at  a  later  period,  and  will  prolong 
their  growth  into  the  autumn. 

2.  That  besides  their  general  relative  value,  as  represented 
in  the  above  table,  each  of  these  substances  has  a  further  spe- 
cial valine  not  here  exhibited,  dependent  upon  the  kind  and 
quantity  of  the  saline  and  other  inorganic  matters  whica 
they  severally  contain.  Thus  three  of  dry  flesh  are  equal  to 
five  of  pigeons'  dung,  in  so  far  as  the  organic  part  is  concerned ; 
but  the  latter  contains  also  a  considerable  quantity  of  bone 
earth  and  of  saline  matter  which  is  present  only  in  minute 
quantity  in  the  former.  Hence  pigeons'  dung  will  benefit  ve- 
getation in  circumstances  where  dry  flesh  would  in  some  degree 
fail.  So  the  liquid  excretions  contain  much  important  saline 
matter  not  present  in  the  solid  excretions — not  present  either 
in  such  substances  as  horn,  wool,  and  hair — and,  therefw-: 


DIFPEEENCE   IN    ANIMAL   AND   VEGETABLE   MANURES.  215 

each  must  be  capable  of  exercising  an  influence  upon  vegetr. 
tion  peculiar  to  itself. 

Hence  the  practical  farmer  sees  the  reason  why  no  one  simple 
manure,  such  as  hair  or  flesh,  can  long  answer  on  the  same  land  ; 
and  why,  in  all  ages  and  countries,  the  habit  of  employing  mixed 
manures  and  artificial  composts  has  been  universally  diffused. 
When  mixed  manures  are  not  employed,  the  kind  of  manure 
which  has  been  used  must,  after  a  time,  be  changed.  A  species 
of  rotation  of  manures  must,  in  fact,  be  introduced,  in  order 
that  a  second  or  third  species  of  manure  may  give  to  the  land 
those  substances  with  which  the  first  was  unable  to  supply  it. 

SECTION   IT. CHEMICAL  DISTINCTION    OR   DIFFERENCE   BETWEEN 

ANIMAL   AND   VEGETABLE   MANURES. 

In  what  do  animal  manures  differ  from  vegetable  manures  ? 
What  is  the  cause  of  this  difference  ?  How  does  the  digestion 
of  vegetable  matter  improve  its  value  as  a  manure  ? 

1.  The  characteristic  distinction  between  animal  and  vegetable 
manures  is  this — that  the  former  contain  a  much  larger 
proportion  of  nitrogen  than  the  latter.  This  will  be  seen  at 
once,  by  comparing  together  the  tables  given  in  the  preceding 
pages,  (184  and  212,)  in  which  the  numbers  given  represent 
the  relative  agricultural  values  of  different  vegetable  and 
animal  substances  compared  with  that  of  farmyard  manure. 
The  lowest  numbers  represent  the  highest  value,  and  the  largest 
amount  of  nitrogen,  and  these  low  numbers  are  always  opposite 
to  the  purest  animal  substances. 

2.  In  consequence  of  their  containing  so  much  nitrogen, 
animal  substances  are  further  distinguished  by  the  rapidity  with 
which,  when  moist,  they  putrefy  or  run  to  decay.  During  this 
decay,  the  nitrogen  they  contain  gradually  assumes  the  form  of 
ammonia,  which  is  perceptible  by  its  smell,  and  which,  when 
proper  precautions  are  not  taken,  is  apt,  in  great  part,  to  escape 
into  the  air.     Hence  the  loss  which  occurs  when  manure  is 


216  CAUSE   OF   DIFFERENCE    BETWEEN  THE   MANURES. 

fermented  too  completely,  or  without  proper  precautions  t« 
prevent  the  escape  of  volatile  substances.  And  as  animal 
manure,  when  thus  over-fermented,  or  permitted  to  give  oif  its 
ammonia  into  the  air,  is  found  to  be  less  active  upon  vegetation 
than  before,  it  is  reasonably  concluded  that  to  this  ammonia, 
and  the  compounds  formed  along  with  it,  or  to  the  substances 
from  which  they  are  produced,  the  peculiar  virtue  of  animal 
manures,  when  rightly  prepared,  is  in  a  great  measure  to  be 
ascribed. 

Vegetable  substances  in  general  do  not  decay  so  rapidly,  and 
emit  little  odor  of  ammonia  when  fermenting.  When  prepared 
in  the  most  careful  way,  also,  vegetable  manure  does  not  exhibit 
the  same  immediate  and  remarkable  action  upon  vegetable 
growth  as  is  displayed  by  almost  every  substance  of  animal 
origin.  There  are  exceptions,  indeed,  to  this  general  rule,  since 
the  crushed  seeds  of  plants — rape-dust  for  example — produce  an 
effect  on  many  crops  little  inferior  to  that  of  animal  manures. 
They,  in  fact,  resemble  animal  substances  very  closely  in  their 
chemical  composition, 

SECTION   Hi. CAUSE   OF    THE    DIFFERENCE    BETWEEN   ANIMAL    AND 

VEGETABLE   MANURES.      EFFECTS   OP   RESPIRATION. 

Whence  do  animal  substances  derive  all  this  nitrogen  ?  Ani- 
mals live  only  upon  vegetable  productions  containing  little 
nitrogen  ;  can  they  then  procure  all  they  require  from  this 
source  alone?  Again,  does  the  act  of  digestion  produce  any 
chemical  alteration  upon  the  food  of  animals  so  as  to  render 
their  excretions  a  better  manure,  richer  in  nitrogen  than  the 
substances  on  which  they  feed  ?  Does  theory  throw  any  light 
upon  the  opinion  generally  entertained  among  practical  men 
upon  this  point  ? 

These  two  apparently  distinct  questions  will  be  explained  by 
a  brief  reference  to  one  common  natural  principle. 

1.  Animals  have  two  necessary  vital  functions  to  perform — tc 


EFFECTS    OF   ANIMAL   DIGESTION,  211 

breathe  and  to  digest.  Both  are  of  equal  importance  to  the 
health  and  general  welfare  of  the  animal.  The  digester  (the 
stomach)  receives  the  food,  melts  it  down,  extracts  from  it  those 
substances  which  are  best  suited  to  supply  the  wants  of  the 
bodj,  and  sends  them  forward  into  the  blood.  The  breathers 
(the  lungs)  sift  the  blood  thus  mixed  up  with  the  newly-digested 
food,  combine  oxygen  with  it,  and  extract  carbon— which  car- 
bon, in  the  form  of  carbonic  acid,  they  discharge  by  the  mouth 
and  nostrils  into  the  air. 

Such  is  a  general  description  of  these  two  great  processes  ; 
their  effect  upon  the  food  that  remains  in  the  body,  and  has  to 
be  rejected  from  it,  is  not  difficult  to  perceive. 

Suppose  an  animal  to  be  full  grown.  Take  a  full-grown  man. 
All  that  he  eats  as  food  is  intended  merely  to  renovate  or 
replenish  his  system,  to  restore  that  which  is  daily  removed  from 
every  part  of  his  body  by  natural  causes.  In  the  full-grown 
state,  everything  that  enters  the  body  must  come  out  of  the  body  in 
one  form  or  another.  The  first  part  of  the  food  that  escapes  is 
that  portion  of  its  carbon  that  passes  off  from  the  lungs  during 
respiration.  This  portion  varies  in  weight  in  different  individuals 
— chiefly  according  to  the  quantity  of  exercise  they  take.  From 
5  to  9  ounces  a-day  is  the  average  quantity  given  off  from  the 
lungs  of  a  full-grown  man,  though  in  periods  of  violent  bodily 
exertion,  13  to  15  ounces  of  carbon  are  breathed  out  in  the 
form  of  carbonic  acid. 

Suppose  a  full-grown  man  to  eat  a  pound  and  a  half  of  bread, 
and  a  pound  of  beef  in  24  hours,  and  that  he  gives  off  by  respi- 
ration 8  ounces  of  carbon  (3500  grains)  during  the  same  tune. 
Then  he  has 

Carbon.  Nitrogen. 

Taken  in  his  food,  about        4500  grains,  and  500  grains,  while 
He  has  given  ofiF  in  res-  )   ^^^^  ^^^  jj^^j^  ^^  ^^  ^.^^ 
piration,        .        .  J  '^ 

Leaving  to  be  converted 
into  his  own  substance,  \- 1000  grains  and   500  grains, 
or  to  be  rejected,   . 
10 


818  VALUE   OF  THE   DUNG. 

Oar  two  conclusions,  therefore,  are  clear.  The  yegetable 
food,  by  respiration,  is  freed  from  a  large  portion  of  its  carbon, 
which  is  discharged  into  the  air,  while  nearly  the  whole  of  the 
nitrogen  remains  behind.  In  the  food  consumed,  the  carbon 
was  to  the  nitrogen  as  9  to  1  ;  in  that  which  remains  in  the 
body  after  respiration  has  done  its  work,  the  carbon  is  to  the 
nitrogen  in  the  proportion  of  only  2  to  1. 

It  is  out  of  this  residue,  rich  in  nitrogen,  that  the  several 
parts  of  animal  bodies  are  built  up.  Hence  the  reason  why 
they  can  be  formed  from  food  poor  in  nitrogen,  and  yet  be  them- 
selves rich  in  the  same  element. 

It  is  this  same  residue  also,  which,  after  it  has  performed  its 
functions  within  the  body,  is  discharged  again  in  the  form  of 
solid  and  liquid  excretions.  Hence  the  greater  richness  in  ni- 
trogen— in  other  words,  the  greater  fertilising  power  possessed 
by  the  dung  of  animals  than  by  the  food  on  which  they  live. 

2.  It  must  also  be  borne  in  mind,  that  the  digested  food  con- 
tains all  the  saline  matter,  as  well  as  nearly  all  the  nitrogen, 
which  had  entered  the  stomach  of  the  animal.  Weight  for 
weight,  therefore,  the  dung  must  be  richer  also  in  saline  matter 
than  the  vegetable  food,  and  therefore  must  be  more  fertilising 
in  its  effects  upon  the  land.  In  an  experiment  made  on  the 
food  and  dung  of  the  horse,  it  was  found  that  while  in  the  dry 
food  the  carbon  was  to  the  saline  matter  as  6  to  1,  it  was  in 
the  dry  dung  only  as  2  to  1. 

3.  Two  other  remarks  I  may  here  add,  because  of  their 
interest  to  the  practical  man. 

a.  The  manure  of  the  cow,  taking  it  mixed,  is  not  so  rich  in 
nitrogen  as  that  of  man.  It  is  true  that  the  cow,  owing  to  its 
larger  bulk  and  larger  lungs,  gives  off  perhaps  eight  or  nine 
times  as  much  carbon  by  respiration  as  an  active  full-grown 
man.  But  the  weight  of  its  daily  food  still  farther  exceeds  that 
of  a  healthy  man.  Suppose  the  daily  food  of  a  cow  to  weigh 
ten  times  as  much  as  the  food  we  have  supposed  a  man  to  eat, 
and  to  contain  carbon  and  nitrogen  in  nearly  the  same  propor- 


DUNG   OF   FULL-GROWN   ANIMALS.  ^19 

tions — and  that  it  gives  oflf  60  ounces  of  carbon  each  day  from 
its  lungs — then  we  have 

Carbon.  Nitrogen. 

In  the  food,  .  .    45,000  grains.  5000  grains. 

Given  oflf  by  the  lungs    .     26,000       "  . .       " 


To  be  ultimately  rejected,     19,000      "  5000    " 

In  the  mixed  manure  rejected  by  such  a  cow,  therefore,  the 
carbon  would  be  to  the  nitrogen  in  the  proportion  of  about  4 
to  1 ;  while  in  nightsoil  it  was,  according  to  our  former  suppo- 
sition, as  2  to  1.  Thus  the  mixed  dung  and  urine  of  the  cow 
is  less  rich  as  an  immediately  acting  manure  than  the  mixed 
nightsoil  and  urine  of  man.  And  since  much  of  the  nitrogen, 
as  well  as  of  the  saline  matter  of  the  food,  is  contamed  in  the 
urine  of  the  cow,  if  this  urine  be  allowed  to  escape,  the  solid 
cow-dung  will  be  still  colder  and  less  fertilising.  The  dry  mixed 
manure  of  the  cow  is  richer  in  nitrogen  than  the  dry  food, 
weight  for  weight,  but  not  so  much  so  as  if  the  cow  gave  off 
from  her  lungs  a  larger  proportion  of  the  carbon  contained  in 
her  food. 

h.  Since  the  parts  of  animals — their  blood,  muscles,  tendons, 
and  the  gelatinous  portion  of  their  bones — contain  much  nitro- 
gen, young  beasts  which  are  growing  must  appropriate  to  their 
own  use,  and  work  up  into  flesh  and  bone,  a  portion  of  the  ni- 
trogen contained  in  the  non-respired  part  of  their  food.  But  the 
more  they  thus  appropriate,  the  less  will  pass  off  into  the  fold- 
yard  ;  and  hence  it  is  natural  to  suppose  that  the  manure,  either 
liquid  or  solid,  which  is  prepared  where  many  growing  cattle 
are  fed,  the  food  being  the  same,  will  not  be  so  rich  as  that  which 
is  yielded  by  full-grown  animals.  This  deterioration  has  actually 
been  observed  in  practice,  and  it  may  with  some  degree  of  cer- 
tainty be  expected  in  all  cases  to  take  place,  unless,  by  giving 
a  richer  food  to  the  young  cattle,  the  difference  to  the  farmyard 
is  made  up.* 

*  Though  I  have  dwelt  as  long  upon  these  interesting,  and,  I  believe^ 


S20  KATINO  OFF  WITH   SHEEP. 


SECTION    IV. IMPROVEMENT    OF    THE    LAND     BY   EATING    OFF   WITH 

SHEEP. 

The  eating  off  with  sheep  is  a  practice  on  which  some  light 
is  thrown  by  the  considerations  presented  in  the  preceding  sec- 
tion. This  practice  is  adopted  in  different  places  with  a  view 
to  very  different  objects. 

1.  On  sandy  soils,  as  in  ISTorfolk,  the  whole  or  part  of  the 
turnip  crop  is  eaten  off  with  sheep,  for  the  purpose  chiefly  of 
treading  down  and  consolidating  the  soil,  and  thus  fitting  it 
for  the  better  growth  of  the  succeeding  crop  of  barley.  The 
production  of  a  mechanical  effect  upon  the  soil  is  here  the  chief 
thing  sought  for. 

2.  When  the  soil  is  not  so  light,  the  turnips  are  often  eaten 
off  with  sheep  for  the  sake  of  the  regular  and  even  manuring 
which  the  land  is  sure  to  obtain.  The  effect  sought  for  here  is 
also  chiefly  mechanical.  The  turnips  could  be  drawn,  and  the 
dung  collected,  but  it  would  afterwards  have  to  be  spread — and 
it  could  not  by  hand  be  so  easily  spread,  or  laid  on  the  land  so 
completely  without  loss. 

3.  Independent  of  the  above  considerations,  the  general  be- 
nefit to  the  land  of  eating  off  with  sheep  arises  from  the  con- 
version of  the  vegetable  pr6duce  into  a  manure  richer,  weight 
for  weight,  in  nitrogen  and  saline  matter,  and,  therefore,  having 
a  more  immediate  and  powerful  effect  upon  the  after  crops.  In 
the  case  of  land  which  is  otherwise  in  good  heart  or  condition, 
perhaps  no  better  or  more  profitable  husbandry  than  this,  for 
rural  districts,  could  readily  be  recommended. 

4.  But  the  manure  is  richer,  as  we  have  seen,  because  the 
respiration  of  the  animal  separates  a  large  proportion  of  the 

novel  considerations,  as  the  limits  of  this  little  -work  will  permit,  yet  for 
ftiller  details,  and  for  perhaps  a  clearer  exposition  of  the  principles  above 
advanced,  I  must  refer  the  reader  to  my  Lectures  on  Agricultural  Chemistry 
and  Geology,  2d  edition. 


EATING   OFF  AGAINST  PLOUGHING  IN.  221 

carbon  which  the  food  contains.  This  fact  throws  light  upon  a 
question  which  the  improving  farmer  has  frequently  asked  him- 
self in  reference  to  poor  or  worn-out  arable  land,  or  to  land  he 
wishes  to  reclaim.  If  I  sow  a  green  crop — rape,  or  buckwheat, 
or  rye,  or  tares — had  I  better  eat  it  off  with  sheep,  or  plough 
it  in  ?  I  am  in  doubt  about  the  effect  of  ploughing  in,  but 
I  am  sure  that  by  eating  off  I  shall  give  the  land  a  good  ma- 
nuring. 

Now  theory  answers  this  question  distinctly.  If  the  only 
object  be  to  enrich  the  ground,  plough  in  green.  By  this  means 
the  carbon  is  saved  which  would  otherwise  be  dissipated  by  the 
lungs  of  the  animal, — and  this  carbonaceous  matter  is  of  great 
value  in  improving  poor,  thin,  or  sandy  soils,  in  which  organic 
matter  is  deficient. 

But  if  enriching  the  soil  be  not  the  sole  object-— if  some  mut- 
ton also  be  desired — then  it  is  good  husbandry  to  eat  off,  with 
full-grown  and  fattening  stock.  The  land  will  improve  less 
rapidly  in  this  way  than  by  ploughing  in,  and  it  will  be  longer 
before  you  can  safely  crop  it  with  corn,  but  it  will  gradually 
improve  under  such  treatment. 

Why  fattening  and  not  growing  stock  is  to  be  kept  on  such 
land  will  appear  from  the  considerations  to  be  presented  in  tho 
concluding  chapter — on  the  feeding  of  animals. 


CHAPTER  XVIL 

B«]ujk>  and  mineral  manures. — The  salts  of  ammonia  as  manures. — Ammo- 
iiia<.«I  liquor,  sal-ammoniac,  and  sulphate  of  ammonia. — Results  of  expe- 
riments with  these  salts. — Quantity  of  nitrogen  required  by  the  wheat 
crop. — Carbonates,  nitrates,  and  silicates  of  potash  and  soda. — Sulphates 
of  potash  and  soda. — Common  salt. — Sulphate  of  magnesia. — Sulphate  of 
iron. — Gypsum. — Use  of  the  phosphate  and  super-phosphate  of  lime,  a:id 
cause  of  their  beneficial  action. — Use  of  kelp,  and  of  the  aslies  of  wood, 
straw,  the  husk  of  oats,  barley,  and  rye,  and  of  the  sugar-can& — Compo- 
Bition  and  use  of  peat  or  Dutch  ashes. — Coal  ashes. 

The  general  nature  and  mode  of  operation  of  such  saline  and 
mineral  substances  as  are  capable  of  acting  as  manures,  will  be 
in  some  measure  understood  from  what  has  already  been  stated 
as  to  the  necessity  of  nitrogen  and  of  inorganic  food  to  living 
plants,  and  as  to  the  kind  of  inorganic  food  which  they  espe- 
cially require.  It  will  be  necessary,  however,  to  advert  briefly 
to  the  more  important  of  these  manures, — their  use,  their  mode 
of  action,  and  the  theory  of  their  observed  effects. 

SECTION  I. — THE  SALTS  OF  AMMONIA  AS  MANURES. 

The  value  of  ammonia  as  a  manure  has  been  already  spoken 
of  (pages  2t  and  52.)  It  exists  in  all  fermenting  animal  ma- 
nures, and  thus  is  constantly  applied  to  the  land  even  in  the 
least  advanced  districts.  There  are  several  states,  however, 
in  which  it  has  lately  begun  to  be  used,  unmixed  with  other 
substances,  and  with  manifest  advantages  to  the  crops. 

1.  Ammoniacal  Liquor. — This  is  water  rich  in  ammonia, 
which  is  distilled  from  coal  during  the  manufacture  of  coal  gas. 
It  is  of  various  degrees  of  strength,  and  therefore,  if  applied  to 
the  land  alone,  it  must  be  diluted  with  a  variable  proportion  of 


CABBONATE    OF   AMMONIA.  223 

water.  It  often  contains  ammonia  enough  to  yield,  when  satu- 
rated with  spirit  of  salt,  as  much  as  a  pound  and  a  half  of  sal- 
ammoniac  from  a  single  gallon.  That  of  the  London  gas- 
works is  said  to  yield,  when  saturated  with  sulphuric  acid, 
about  14  ounces  of  sulphate  of  ammonia  from  the  gallon. 

To  grass  land  this  ammoniacal  liquor  may  be  applied  with 
great  advantage,  by  means  of  a  water-cart — ^being  previously 
diluted  with  from  three  to  five  times  its  bulk  of  water.  If  too 
strong  it  will  burn  up  the  grass  at  first,  especially  if  the  wea- 
ther be  dry;  but,  on  the  return  of  rain,  the  herbage  will  again 
spring  up  with  increased  luxuriance. 

On  arable  land  it  may  be  applied  with  profit  to  the  young 
wheat  or  other  corn  by  the  water-cart,  or  it  may  be  dried  up 
by  any  porous  material,  and  thus  put  into  the  turnip  or  potato 
drills.  A  friend  in  Northamptonshire  writes  me  that  the  200 
gallons  of  ammoniacal  liquor  per  imperial  acre,  drunk  up  by 
sawdust  and  put  into  the  drills,  has  alone  given  him  an  excel- 
lent crop  of  turnips.  This  manuring,  however,  cannot  be  ex- 
pected to  keep  the  land  in  heart.  A  certain  proportion  of 
bone-dust  should  be  mixed  with  this  ammoniated  sawdust,  or 
else  the  corn  crops  should  afterwards  be  top-dressed  with  rape- 
dust,  guano,  or  bones.  If,  indeed,  the  land  be  already  hone- 
sick^  the  saturated  sawdust  may  be  used  alone,  or  with  a  mix- 
ture of  wood  or  peat  ashes  for  one  rotation. 

The  ammoniacal  liquor  may  also  be  used  advantageously  to 
promote  the  fermentation  of  peat,  sawdust,  and  other  com- 
posts,— or  it  may  be  added  to  the  ordinary  dunghill,  or  to  the 
liquid  manure  of  the  farmyard,  and  applied  along  with  it  to 
the  land. 

It  is  said  to  extirpate  moss  from  old  grass  land  more  perma- 
nently than  lime. 

2.  Carbonate  of  ammonia  is  the  common  smelling  salts  of  the 
shfips.  It  exists  in  the  ammoniacal  liquor  above  described,  and 
ie  'ery  useful,  in  a  diluted  state,  in  promoting  vegetation.  It 
it    (CO  expensive,  however,  in  the  form  in  which  it  is  at  present 


224  STEEPING    SEEDS    IN    SALTS   OF   AMMONIA. 

sold,  to  be  of  much  use  to  the  practical  farmer.  An  ounce  of 
it,  dissolved  in  a  gallon  of  water,  gives  a  solution  which 
destroys  insects  on  rose-trees  and  other  plants,  and  adds  to  their 
luxuriance  at  the  same  time.  A  few  pieces  laid  on  a  plate  and 
allowed  to  evaporate  slowly  into  the  atmosphere  of  a  conserva- 
tory, are  said  to  add  greatly  to  the  green  and  healthy  appear- 
ance of  the  plants. 

3.  Sal-ammoniac. — The  same  may  be  said  of  muriate  of  ammo- 
nia, the  sal-ammoniac  of  the  shops.  Though  experiment  has 
shown  that  this  substance  exercises  a  very  beneficial  influence 
on  the  growth  of  our  cultivated  crops,  yet  the  pure  salt  is  too 
high  in  price  to  admit  of  its  being  economically  used  in  ordinary 
husbandry.  An  impure  variety,  however,  is  prepared  from  gas 
liquor,  which  is  sold  at  about  15s.  a  cwt. 

4.  Sulphate  of  ammonia  is  now  manufactured  at  a  compara- 
tively cheap  rate,  and  is  sold  at  iB16  a  ton.  This  salt  may  be 
applied  with  advantage,  especially  to  soils  which  are  locally 
called  </«a/— which  contain,  that  is,  much  inert  vegetable  matter, 
and  to  such  as  are  naturally  rich  in  phosphates.  It  may  also 
be  mixed  with  bones,  rape-dust  or  wood-ashes,  and  put  into  the 
turnip  or  potato  drills,  or  it  may  be  used  as  a  top-dressing  in 
spring  to  sickly  crops  of  corn. 

A  case  is  mentioned  of  a  field  being  manured  for  wheat,  in 
part  with  ordinary  farmyard  manure,  and  in  part  with  1|  cwt. 
per  imperial  acre  (cost  £.1  2s.)  of  sulphate  of  ammonia — when 
the  produce  of  the  former  was  24,  and  of  the  latter  33  bushels 
per  imperial  acre.  In  other  cases,  also,  it  has  been  found  a 
profitable  application,  both  to  young  corn  and  to  meadow  hay. 

Faded  flowers,  when  introduced  into  a  solution  of  sulphate  of 
ammonia,  are  said  to  be  perfectly  restored  and  revivified. 

5.  Steeping  of  seeds  in  the  salts  of  ammonia. — The  salts  of 
ammonia,  especially  sal-ammoniac  and  the  sulphate  of  ammonia, 
have  been  strongly  recommended  as  steeps  for  seed-corn.  I'hey 
have  in  many  cases  been  found  very  advantageous  in  hastening 
germination,  and  in  increasing  the  after  luxuriance  of  the  crop 


EXPERIMENTS   UPON   WHEAT.  **  225 

Thus,  in  one  experiment,  seeds  of  wheat,  steeped  in  the  sulphate 
of  ammonia  on  the  5th  of  July,  had  by  the  10th  of  August 
tillered  into  nine,  ten,  and  eleven  stems  of  nearly  equal  vigor, 
while  unprepared  seed  had  not  tillered  into  more  than  two, 
three,  or  four  stems. 

Sal-ammoniac  has  a  similar  effect.  In  Upper  India  it  is  pre- 
pared by  heating  together  camel's  dung  and  sea  salt,  and  is  used 
in  the  plains,  among  other  purposes,  for  the  steeping  of  seeds. 

It  is  to  be  observed,  however,  that  neither  when  applied 
directly  as  a  manure  to  the  growing  crops,  nor  when  used  as  a 
steep  for  the  seed,  can  the  salts  of  ammonia  alone  bring  a  plant 
to  maturity.  They  tend  to  hasten  its  growth,  if  all  its  other 
wants  can  he  readily  supplied  ly  the  soil ;  but  if  this  is  not  the 
case,  a  quick  decay  will  succeed  to  a  short-lived  luxuriance. 

SECTION  II. — RESULTS  OF  EXPERIMENTS  WFTH  THE  SALTS  OF  AMMONIA 
NITROGEN  NECESSARY  TO  THE  WHEAT  CROP. 

The  last  mentioned  fact,  as  well  as  the  general  value  of  the 
salts  of  ammonia,  is  illustrated  by  the  results  of  some  experi- 
ments made  by  Mr.  Lawes  at  Rothampstead  in  Hertfordshire. 
He  sowed  wheat  for  three  successive  years  on  the  same  piece  of 
ground,  applying  only  mineral  manures  the  first  year,  and  only 
ammoniacal  manures  the  second  and  third  years.  The  following 
were  the  results  : — 

Application  per  imperial  acre.  Grain''"°*^'^°^'  Straw 

""•  irs'oT^'.ti,:"^!'    'fo'"-!   1"-^-    "i^i"- 

1846.    Sulphate  of  ammonia,  2      ..  21    . .  2244  . . 

TBus  upon  a  soil  already  rich  in  mineral  manure,  the  applica- 
cation  of  salts  of  ammonia  nearly  doubled  the  crop  of  grain  in 
1845,  and  quadrupled  that  of  straw  ;  and,  in   1846,   added 
10* 


NITRATES  OP  POTASH  AND  SODA. 

again  one-half  to  the  grain  above  1844,  and  doubled  the  straw. 
In  each  case,  however,  some  allowance  must  probably  be  made 
for  the  influence  of  natural  varieties  in  the  seasons. 

As  to  the  necessity  of  nitrogen  to  the  wheat  crop,  Mr. 
Lawes  concludes,  from  numerous  experiments,  that,  upon  his 
soil  and  in  his  locality,  five  pounds  of  ammonia — or  four  of  ni- 
trogen, in  some  other  available  form — are  "  required  for  the 
production  of  every  bushel  of  wheat  beyond  the  natural  yield 
of  the  soil  and  the  season."*  But  as  a  bushel  of  wheat  con- 
-  tains  only  about  1  lb.  of  nitrogen,  (equal  to  14^  lb.  of  ammonia,) 
it  is  obvious  that,  if  this  estimate  be  correct,  the  greater  part 
of  the  nitrogen  is  lost  to  the  farmer.  The  subject,  therefore, 
is  open  to  further  investigation. 

SECTION  in. SALTS  OF  POTASH,  SODA,  MAGNESU,  AND  IRON. 

1°.  Carbonate  of  potash  and  soda. — The  common  pearl-ash, 
and  the  common  soda  of  the  shops,  have  not  in  this  state  been 
much  employed  in  agriculture.  Both,  however,  greatly  pro- 
mote the  growth  of  strawberries  in  the  garden, — and  the  latter 
is  now  cheap  enough  (10s.  a  cwt.)  to  admit  of  its  being  tried 
as  a  top-dressing  on  clovers  and  grass  lands,  on  such  as  are  old 
and  mossy  especially,  with  every  prospect  of  advantage.  It 
should  be  dissolved  in  much  water,  and  put  on  with  a  water- 
cart,  or  thoroughly  mixed  with  earth,  and  applied  as  a  top- 
dressing.  Mixed  at  the  rate  of  one  cwt.  an  acre,  with  bone  or 
rape  dust,  or  even  with  guano,  it  may  be  expected  to  improve 
both  the  turnip  and  the  potato  crops. 

Carbonate  of  soda,  in  the  form  of  soda  ash,  has  been  appUed 
with  success  to  kill  or  to  remove  the  effects  of  the  wire-worm. 
It  may  either  be  sown  with  the  wheat  in  winter,  or  applied  as 
a  top-dressing  in  the  spring,  to  the  affected  wheat  or  oats. 

2°.  Nitrates  of  potash  and  soda. — Saltpetre  and  nitrate  of 

*  Joumai  of  Roy (H  AgricvUural  Society  of  England,  viiu  246. 


COMMON    SALT.  227 

soda  have  been  deservedly  commended  for  their  beneficial  ac- 
tion, especially  upon  yoxmg  vegetation.  They  are  distinguished, 
like  the  salts  of  ammonia,  for  imparting  to  the  leaves  a  beautiful 
dark  green  color,  and  are  applied  with  advantage  to  grass  and 
young  corn  of  any  kind,  at  the  rate  of  1  cwt.  to  1|  cwt.  per 
acre.  They  are  said  even  to  benefit  young  fir-trees.  Applied 
to  young  sugar-canes  they  have  been  found  largely  to  increase 
the  crop,  and  even,  in  the  second  year  after  their  application, 
to  add  much  to  the  luxuriance  of  the  cane  fields.  The  nitric 
acid  they  contain  yields  nitrogen  to  the  plant,  while  potash  and 
soda  are  also  put  within  reach  of  its  roots,  and  no  doubt  serve 
many  beneficial  purposes.  IJpon  land  rich  in  phosphates,  ni- 
trate of  soda  is  a  profitable  application  to  wheat,  being  found, 
in  Norfolk,  to  return  an  increase  of  from  4  to  7  bushels  of  grain 
for  every  cwt.  applied  to  the  corn  in  spring.*  It  is  especially 
recommended  for  wheat,  on  light,  gravelly,  and  sandy  soils,  and 
on  cold  undrained  clays. 

3°.  Sulphate  of  potash  is  likely  to  be  useful,  especially  to 
root  and  leguminous  crops.  Its  price,  however,  is  usually  high, 
varying  from  £12  to  £20  a  ton. 

4°.  Common  salt  has,  in  many  districts,  a  fertilising  influence 
upon  the  soil.  It  destroys  small  weeds;  improves  the  quality 
of  pastures,  and  renders  them  more  palatable ;  strengthens  and 
brightens  the  straw,  and  makes  the  grain  heavier  per  bushel, 
both  of  wheat  and  oats.  It  has  been  observed,  also,  to  pro- 
duce specially  good  effects  upon  mangold-wurtzel. 

A  small  quantity  of  salt  is  absolutely  necessary  to  the  healthy 
growth  of  all  our  cultivated  crops,  but  it  is  in  inland  and  shel- 
tered situations,  and  on  high  lands  often  washed  by  the  rains, 
that  its  effect  is  likely  to  be  most  appreciable.  The  spray  of 
the  sea,  borne  to  great  distances  by  the  winds,  is  in  many  dis- 
tricts, where  prevailing  sea  winds  are  known,  sufficient  to  sup- 
ply an  ample  annual  dressing  of  common  salt  to  the  land.f 

*  See  the  Author's  Lectures  on  Agricultural  Chemistry,  2d  edition. 
\  At  Penicuik,  near  Edinburgh,  the  rain  that  falls  contains  so  much  eom- 
mon  salt  as  alone  to  convey  640  lb.  to  every  acre  in  a  year.— (Dr.  Madden.) 


ZZO  SULPHATES   OF   MAGNESIA   AND   IRON. 

It  has  sometimes  been  found  to  be  of  still  more  advantage, 
in  strengthening  the  straw,  to  apply  a  mixture  of  quicklime 
with  a  fourth  or  a  fifth  part  of  its  weight  of  dry  salt;  or  the 
salt  may  be  dissolved  in  water,  and  the  lime  heap  slaked  with 
the  solution — or  sea  water  may  be  at  once  employed  to  slake 
the  lime. 

5°.  Sulphate  of  soda,  or  Glauber's  salt,  has  lately  been  re- 
commended in  this  country  for  clovers,  grasses,  and  green  crops. 
Mixed  with  nitrate  of  soda  it  produces  on  some  soils  remarka- 
ble crops  of  potatoes,  and  in  some  localities,  when  used  alone, 
it  has  greatly  benefited  the  turnip  crop.  Mr.  Girdwood  found 
that  1^  cwt.  of  this  sulphate  per  acre,  sprinkled  upon  the  other 
manure  in  the  drills,  added  16  bushels  an  acre  to  his  crop  of 
beans.  It  is  on  rich  land  only,  however,  that  the  addition  of  a 
single  saline  substance  can  be  expected  to  produce  results  so 
favorable  as  this. 

6".  Silicates  of  potash  and  soda. — When  potash  and  soda  are 
melted  together  with  silicious  sand,  they  form  a  kind  of  glass 
which  is  soluble  in  water.  This  has  produced  remarkable 
effects  upon  the  potato  crop,  and,  like  other  silicates,  is  recom- 
mended as  a  strengthener  of  the  straw  of  our  corn  crops. 

1°.  Sulphate  of  magnesia,  or  Epsom  salts,  is  also  beneficially 
applied  in  agriculture  to  clovers  and  corn  crops.  It  can  be  had 
in  pure  crystals  at  10s.  a  cwt.,  and  in  an  impure  state  at  from 
3s.  to  6s.  a  cwt.  It  has  been  found  of  advantage  as  a  top- 
dressing  for  the  young  wheat,  and  as  an  application  to  the 
potato.  Where  the  soil  is  deficient  in  magnesia,  it  may  always 
be  expected  to  improve  the  crops  of  com. 

8°.  Sulphate  of  iron. — Common  green  vitriol,  applied  in  the 
form  of  a  weak  solution,  has  been  observed  to  strengthen  feeble 
plants,  and  to  give  them  a  brighter  green.  It  has  also  been 
used  as  a  top-dressing  for  grass,  and  as  an  application  to  dis- 
eased fruit  trees.    It  deserves  a  further  trial. 


GYPSUM   AND    OTHER   SULPHATES.  229 


SECTION  IV. USE  OP  THE  SULPHATE  AND  PHOSPHATES  OF   LIME,  AND 

CAUSE  OF  THEIR  BENEFICIAL  ACTION. 

1°.  Sulphate  of  lime,  or  gypsum,  is  in  Germany  applied  to 
grass  land  with  great  success,  and  over  large  tracts  of  country. 
In  the  south  of  England  it  has  been  applied  to  some  grass  lands 
with  benefit  for  thirty-five  years  in  succession,  at  the  rate  of  2| 
cwt.  per  acre.  It  supplies  the  lime  and  sulphuric  acid  annually, 
which  are  annually  removed  by  the  crop.  In  the  United  States 
it  is  used  for  every  kind  of  crop  ;  and  I  have  there  seen  it  pro- 
duce very  striking  effects  on  Indian  corn.  It  is  especially 
adapted  to  the  pea,  the  bean,  and  the  clover  crops.  It  is  more 
sensibly  efficacious  when  applied  in  the  natural  state  than  after 
it  is  burned. 

The  sulphates  all  aiBford  sulphur  to  the  growing  plant,  while 
the  lime,  soda,  magnesia,  &c.,  which  they  contain,  are  themselves 
in  part  directly  appropriated  by  it,  and  in  part  employed  in  pre- 
paring other  kinds  of  food,  and  in  conveying  them  into  the 
ascending  sap. 

Though  there  can  be  no  question  that  these  sulphates,  and 
other  similar  substances,  are  really  useful  to  vegetation,  yet  the 
intelligent  reader  will  not  be  surprised  to  find,  or  to  hear,  that 
this  or  that  mineral  substance  has  not  succeeded  in  benefiting 
the  land  in  this  or  that  district.  If  the  builder  has  already 
bricks  enough  at  hand,  he  needs  mortar  only,  to  enable  him  to 
go  on  with  his  work  :  so,  if  the  soil  contain  gypsum  or  sulphate 
of  magnesia  in  sufficient  natural  abundance,  it  is  at  once  a  need- 
less and  a  foolish  waste  to  attempt  to  improve  the  land  by  add- 
ing more  ;  it  is  still  more  foolish  to  conclude,  because  of  their 
failure  in  one  spot,  that  these  same  saline  compounds  are  unlikely 
to  reward  the  patient  experimenter  in  other  localities. 

2°.  Phosphates  of  lime. — a.  Burned  bone. — When  bones  are 
burned  in  an  open  fire,  they  diminish  in  weight  about  one-half, 
and  leave  behind  a  white  earthy  matter  long  known  by  the  name 


180  ACID   OR   SULPHATE   OP   LIME. 

of  bane  earth.  This  bone  earth  consists  chiefly  of  phosphate  of 
lime  (page  193.) 

Bones  are  known  to  be  an  excellent  manure,  and  as  our  cul- 
tivated crops,  and  especially  our  corn  crops,  contain  much  phos- 
phoric acid,  it  has  been  justly  concluded  that  part  of  their  effect 
is  due  to  the  bone  earth  they  contain.  Hence  the  use  of  burned 
bones  as  a  manure  has  been  warmly  recommended. 

In  soils  which  are  poor  in  phosphate  of  lime,  there  is  no  doubt 
but  burned  bones  will  be  likely  to  benefit  the  crops  of  corn  ; 
but  there  are  few  soils,  I  think,  in  which  a  ton  of  bone-dust 
would  not  produce  a  better  effect  than  the  ash  left  by  an  equal 
weight  of  bones. 

b.  Native  phosphate  of  lime. — Phosphate  of  lime  is  found  as 
a  native  mineral  in  many  countries,  and  has  been  applied  with 
advantage  to  the  soil.  It  has  lately  been  met  with  in  tbo  States 
of  New  York  and  New  Jersey  in  sufficient  quantity  to  maKe  it 
likely  to  prove  a  profitable  article  of  import  into  this  country. 
It  has  also  been  discovered  in  considerable  quantity  in  the  marls 
of  the  crag  and  green-sand  formations  (seep.  94,)  of  England, 
and  is  now  dug  up  in  large  quantities  for  agricultural  purposes.* 
In  our  ordinary  lunestones  it  also  exists  in  variable  quantity. 
In  a  burned  lime  from  Carluke,  which  is  full  of  fossils,  I  have 
found  it  to  the  extent  of  2  J  per  cent ;  so  that  every  ton  of  such 
lime  conveys  to  the  land  as  much  phosphate  of  lime  as  two 
bushels  of  bones.  This  must  modify  in  a  favorable  manner  the 
effect  of  such  lime  when  applied  to  the  land. 

c.  Add  or  super-phosphate  of  liine. — When  burned  bones  are 
digested  with  sulphuric  acid  diluted  with  three  times  its  bulk  of 
water,  gypsum  (sulphate  of  lime)  is  produced,  and  falls  to  the 
bottom  of  the  solution,  while  the  phosphoric  acid,  and  a  portion 
of  the  lime,  remain  in  the  sour  liquid  above  it.  When  this 
liquid  is  boiled  down  or  evaporated  to  dryness,  it  leaves  a  white 
powder,  which  is  known  by  the  name  of  acid  or  super-phosphate 

*  Journal  of  the  Eoyal  Agricultural  Society,  voL  ix.  p.  56,  and  vol  xii.  p.  93, 


ASHES   OF   SEA-WEED,    "WOOD   AND    STRAW.  2S1 

of  lime.  Under  the  latter  name  it  has  been  introduced  into  the 
manure  market.  It  is  extensively  manufactured  in  this  country, 
by  grinding  the  mineral  phosphate  obtained  from  the  crag  of 
Norfolk  and  Suffolk,  (p.  93,)  mixing  it  with  about  an  equal 
weight  of  strong  sulphuric  acid,  and  then  drying  the  whole. 
Some  manufacturers  mix  a  portion  of  bone  dust  with  the  mine- 
ral powder,  and  thus  produce  a  manure  containing  some  animal 
matter,  and  therefore  of  more  general  utility. 

As  the  ordinary  burned  bones  are  difficult  to  dissolve  in  the 
soil,  and  as  the  acid  phosphate  is  more  easy  of  solution,  it  is 
likely  to  be  taken  up  more  readily  by  the  roots,  and  thus  more 
rapidly  to  aid  the  growth  of  plants.  These  super-phosphates 
are  sold  at  present  at  about  £*l  a  ton. 

Numerous  experiments  have  been  made  with  the  super-phos- 
phate, and  very  remarkable  results  have  been  Obtained  by  its 
use,  chiefly  as  a  manure  for  the  turnip  crop,  but  also  as  a  top- 
dressing  for  grass,  and  for  wheat,  and  other  kinds  of  corn. 
What  is  sold  as  super-phosphate  by  the  manufacturers,  is  very 
variable  in  its  composition,  and  is  often  largely  adulterated. 

SECTION  v. OF  THE  ASHES  OF  SEA-WEED,  WOOD,  STRAW,  THE  HUSK 

OF  OATS,  BARLEY,  AND  RICE,  AND  OF  THE  SUGAR  CANE. 

1.  Kdp  is  the  ash  left  by  the  burning  of  sea-weed.  It  con- 
tains potash,  soda,  lime,  silica,  sulphur,  chlorine,  iodine,  and 
several  other  of  the  inorganic  constituents  of  plants  which  are 
required  by  them  for  food.  It  is  nearly  the  same  also — with 
the  exception  of  the  organic  matter  which  is  burned  away-^ 
with  the  sea-weed  which  produces  such  remarkably  beneficial 
effects  upon  the  soil.  In  the  "Western  Isles  a  method  is  prac- 
tised of  half-burning  or  charring  sea-weed,  by  which  it  is  pre- 
vented from  melting  together,  and  is  readily  obtained  in  the 
form  of  a  fine  black  powder.  The  use  of  this  variety  ought  to 
combine  the  beneficial  action  of  the  ordinary  saline  constituents 
of  kelp,  in  feeding  or  preparing  food  for  the  plant,  v/ith  the 


382  LIXIVIATED   WOOD   AND    STRAW   ASHES. 

remarkable  properties  observed  in  animal  and  vegetable  char- 
coal. In  Jersey,  the  sea-weed  is  dried  and  burned  in  the 
kitchen  grates,  and  the  ash  is  considered  to  be  efficacious  in 
destroying  grubs.  In  the  Orkneys,  potatoes  are  raised  by 
means  of  a  mixture  of  peat  ashes  and  kelp,  applied  at  the  rate 
of  fifty  bushels  to  the  Scotch  acre. 

2.  Wood  ash  contains,  among  other  substances,  a  portion  of 
common  pearl  ash  in  an  impure  form,  mixed  with  sulphate  and 
silicate  of  potash.  These  substances  are  all  valuable  in  feeding 
and  in  preparing  the  food  of  plants,  and  hence  the  extensive 
use  of  wood  ash  as  a  manure  in  every  country  where  it  can 
readily  be  procured.  Wood  ash,  applied  alone,  is  especially 
beneficial  to  clovers,  beans,  and  other  leguminous  plants.  Mixed 
with  bones  in  nearly  equal  bulk,  it  is  extensively  employed  in 
this  country  as  a  manure  for  turnips.  In  some  soils  it  has  been 
found,  without  any  admixture,  to  raise  large  crops  of  potatoes. 
In  Persia,  seed  wheat  and  melon  seeds  are  always  steeped,  for 
24  hours  before  sowing,  in  a  ley  of  wood  ashes.  In  Lower 
Canada,  40  bushels  of  wood  ashes  applied  alone,  give  a  crop  of 
200  to  250  bushels  of  potatoes. 

3.  Lixiviated  wood  ash.—When  the  common  wood  ash  is 
washed  with  water  as  long  as  any  thing  dissolves,  and  the  solu- 
tion is  then  boiled  to  dryness,  the  common  potash  of  commerce 
is  obtained.  But  a  large  portion  of  the  ash  remains  behind  un- 
dissolved, and  in  countries  where  much  wood  is  burned  for  the 
manufacture  of  potash,  this  lixiviated  or  washed  refuse  accumu- 
lates. It  consists  of  silicate  of  potash  mixed  with  silicate, 
phosphate,  and  carbonate  of  lime,  and  when  applied  to  the 
land  is  remarkably  favorable  to  oats.  It  suits  better  for  clay 
lauds,  and  when  laid  on  in  considerable  quantity,  ( 1  or  2  tons 
to  the  acre,)  its  effects  have  been  observed  to  continue  for  15 
or  20  years.     (Sprengel.) 

4.  Straw  ashes. — In  this  country  straw  is  seldom  burned  for 
the  ash.  In  Germany,  rye-straw  is  not  unfrequently  burned, 
and  the  ash  employed  as  a  top-dressing.    The  dry  straw  is 


ASHES   OF    OATS,    BARLEY,    RICE   AND   CANE   HUSKS.  233 

strewed  over  the  field,  then  burned,  and  the  ash  ploughed  in  on 
the  spot.  In  many  countries — among  others,  in  some  parts  of  the 
United  States — the  straw  is  often  burned,  and  the  ash  scattered 
to  the  wind.  When  it  is  too  much  trouble  to  ferment  the 
straw  in  the  farmyard,  labor  might  surely  be  spared  to  strew 
the  ash  upon  the  fields  from  which  the  crop  was  taken.  Tho 
soil  would  not  fail  to  give  a  grateful  return. 

5.  Ash  of  the  husk  of  oats,  barley,  and  rice. — The  husk,  seeds, 
or  shellings  of  oats  or  barley,  being  supposed  to  contain  na 
nourishment,  are  often  burned  for  the  purpose  of  heating  the 
kiln  on  which  the  grain  is  dried.  When  thus  burned,  these 
husks  leave  a  considerable  quantity  of  a  white  or  grey  ash. 
The  oat  husk  I  find  to  leave  about  5|  per  cent  of  its  weight. 
This  ash  has  hitherto  been  neglected  by  the  millers,  being  ge- 
nerally thrown  into  the  stream  by  which  their  mills  are  worked. 
It  should,  however,  be  carefully  preserved.  It  may  be  ex- 
pected to  prove  a  valuable  top-dressing  to  meadow  land,  to 
young  corn  crops,  and  especially  to  bog  oats.  One  miller  in 
the  north  of  Scotland  informs  me  that  he  makes  about  two 
bushels  a  day  of  ash  from  the  husk  of  the  oats  he  grinds.  The 
waste  of  this  ash,  long  persevered  in,  can  scarcely  have  failed 
slowly  to  impoverish  the  adjoining  land. 

In  China,  India,  and  other  countries  where  rice  is  grown, 
the  husk  of  this  grain  also  is  burned;  but  the  ash  is  rarely 
afterwards  returned  to  the  soil.  In  China,  it  is  said  to  be  em- 
ployed in  the  making  of  certain  articles  of  manufacture. 

6.  Cane  ash. — The  sugar-cane  when  brought  from  the  mill  in 
the  state  of  trash,  is  burned  for  the  purpose  of  boiling  down 
the  syrup.  The  ash  left  by  it  is  rich  in  those  saline  substances, 
without  which  the  cane  cannot  thrive.  Without  having  per- 
sonally examined  any  of  our  West  India  plantations,  I  may 
safely  hazard  the  opinion  that  some,  at  least,  of  the  exhaustion 
complained  of  by  the  planters  is  owing  to  the  neglect  of  this 
valuable  ash — and  that  the  large  importation  of  foreign  ma- 
nures, now  had  recourse  to,  might  by  and  by  be  in  some  mea- 


^34  PEAT  ASHES   FROM  PAISLET. 

sure   dispensed  with,   by  carefully  collecting,   grinding,  ana 
returning  it  to  the  soil. 

SECTION  VI. COMPOSITION   AND   USE   OF   PEAT   OR   DUTCH   ASHES. — 

COAL  ASHES. 

Peat  or  Dutch  ashes  are  the  ashes  of  peat  burned  for  the 
purpose  of  being  applied  to  the  land.  They  vary  in  composi- 
tion with  the  kind  of  peat  from  which  they  have  been  prepared. 
They  often  contain  traces  of  potash  and  soda,  and  generally  a 
quantity  of  gypsum  and  carbonate  of  lime,  a  trace  of  phos- 
phate of  lime,  and  much  silicious  matter.  In  almost  every 
country  where  peat  abounds,  the  value  of  peat  ashes  as  a  ma- 
nure has  been  more  or  less  generally  recognised.  The  following 
analyses  of  two  samples  of  such  ashes  from  the  Paisley  moss, 
and  of  two  from  the  island  of  Lewis,  all  examined  in  my  labo- 
ratory, show  how  valuable,  and,  at  the  same  time,  how  very 
different  in  quality,  such  ashes  may  be,  even  when  they  are  ob- 
tained from  the  same  locality. 

a.  Ashes  from  the  Paisley  moss. 

White  Peat        Black  Peat 
Ashes.  Ashes. 

Charcoal,        -        -        -        -  64.12  3.02 

Sulphates  and  carbonates  of  potash, 
soda,  and  magnesia,  -        -        - 

Alumina, 

Oxide  of  iron,       .        -        .        - 
Sulphate  of  hme,   -        -        -        - 
Carbonate  of  ditto, 
Phosphate  of  ditto,         ... 
SiUcious  matter,  ... 

99.10  98.36 

It  will  be  observed  that  the  first  of  these  contained  more 
than  half  its  weight  of  unburned  charcoal,  and  still  was  richer 
than  the  other,  weight  for  weight,  both  in  soluble  salts  and  in 
phosphate  of  lime — two  of  their  most  valuable  ingredients. 


6.57 

5.16 

2.99 

2.48 

4.61 

18.66 

10.49 

21.23 

8.54 

3.50 

0.90 

0.40 

10.88 

^3.91 

PEAT  ASHES  FROM  LEWIS.  235 

The  reason  of  this  is,  that  the  white  peat,  being  nearer  the 
surface,   consists  of  vegetable  matter   less  decomposed.     The 
ashes  of  the  upper  layers  of  peat,  therefore,  will  generally  be 
more  valuable  than  those  of  the  under  layers. 
b.  Ashes  from  the  island  of  Lewis. 

Chloride  of  sodium,  (common  salt,) 
Phosphate  of  lime. 
Sulphate  of  lime,  (gypsum,)     - 
Sulphate  of  magnesia^ 


^"l^T'^      1         )   in  state  of  silicate 
Potash  and  soda,      V      ^nd  carbonate, 
Alumuia,  ;  ' 

Oxide  of  iron,  ... 

Silica,  soluble  in  caustic  potash, 
Insoluble  silicious  matter  and  sand,     - 
Carbonic  acid,  charcoal,  and  loss, 


0.41 

0.29 

2.46 

6.51 

28.66 

16.85 

1.68 

2.01 

(    6.32 

5.86 

-     5.32 

3.59 

1  11.63 

7.64 

9.18 

6.58 

15.55 

28.58 

7.94 

14.20 

10.85 

7.99 

100.  100. 


These  samples,  again,  present  other  differences.  They  con- 
tain, in  addition  to  the  alkaline  matter  and  the  gypsum,  a  more 
considerable  proportion  of  phosphate  of  lime  than  the  others. 
In  the  one,  the  phosphate  amounts  to  6|  per  cent,  and  must 
contribute  materially  to  its  fertilising  value.  The  soluble  silica 
is  also  deserving  of  notice,  as  likely  to  be  useful — especially  to 
grass  land  and  to  crops  of  corn. 

Peat  ashes  are  not  unfrequently  used  alone,  and  with 
success,  for  the  raising  of  turnips.  Much  of  their  success, 
however,  will  depend  on  the  peculiar  composition  of  the  ashes 
employed. 

In  Lancashire,  peat  only  half  burned  is  considered  preferable 
to  double  the  quantity  burned  to  a  perfect  ash. 

Coal  ashes  consist  in  general  of  alumina  and  silica  mixed 
with  a  variable  proportion  of  gypsum,  carbonate  of  lime,  phos- 
phate of  lime,  and  oxide  of  iron,  mixed  with  half-burned  coal. 
They  vary,  however,  with  almost  every  different  kind  of  coal 
'.iat  is  burned. 


CHAPTER  XVIII. 

Why  saline  manures  are  required  by  the  soil. — Mode  of  determining  their 
local  value. — Circumstances  necessary  to  insure  the  successful  application 
of  saline  manures. — Of  saline  manures  which  exercise  a  special  or  specific 
action  upon  plants. — Results  of  experiments  with  mixed  saline  manures, 
made  with  the  view  of  increasing  the  crop  or  of  affecting  its  quality. — 
Artificial  mixtures  in  imitation  of  valuable  natural  manures. — Recipe  for 
artificial  guano. 

SECTION  I. WHY  SALINE  MANURES  ARE  REQUIRED  BY  THE  SOIL. 

The  use  of  saline  substances  as  manures  is  of  comparatively 
recent  introduction.  In  many  districts,  however,  they  are  indis- 
pensable, if  we  wish  to  maintain  the  present  condition,  or  to 
restore  the  ancient  fertility  of  the  land.  This  will  appear  from 
the  following  considerations  : 

1.  These  saline  substances  exist  in  all  plants,  and  must  there- 
fore abound,  to  a  certain  extent,  in  all  soils  in  which  plants  can 
be  made  to  grow. 

2.  The  rains  gradually  wash  out  from  the  surface — especially 
of  undrained  arable  soils,  and  in  inland  districts — a  portion  of 
the  saline  matter  they  contain.  If  the  surface  soil  is  to  be 
retained  in  its  present  condition,  this  natural  waste  must,  by 
some  means  or  other,  be  supplied. 

3.  The  crops  we  carry  off  the  land  remove  also  a  portion  of 
this  saline  matter  from  the  soil,  and  thus  gradually  impoverish 
it,  if  the  saline  substances  be  not  again  brought  back. 

4.  And  though  we  return  to  the  soil,  in  the  form  of  farmyard 
manure,  all  the  straw  of  our  corn  crops  and  the  dung  of  our 
cattle,  land  still  loses  all  that  we  carry  to  market,  and  all  that 
escapes  from  our  farmyards  and  dung-heaps  in  the  form  of  liquid 


..OCAL   VALUE   OF    SALINE   MANURES.  23*1 

mannre.  Even  where  tanks  for  liquid  manure  are  erected,  the 
farmer  can  never  return  to  the  land  all  the  saline  substances 
contained  naturally  even  in  his  straw.  The  rains  that  fall,  were 
there  no  other  cause  of  waste,  would  wash  away  some  portion 
of  what  he  would  desire  to  carry  back  into  his  field. 

The  necessary  waste  of  saline  matter,  arising  from  the  above 
causes,  must  be  supplied  from  some  source  or  other.  When,  for 
a  long  period  of  time,  the  land  has  maintained  its  fertility  with- 
out receiving  any  artificial  supply,  it  must  contain  within  itself 
naturally  a  very  large  proportion  of  these  substances — ^must 
derive  from  springs  a  continued  accession  of  such  matter,  or 
from  waters  that  flow  down  from  a  higher  level  and  bring  with 
them  the  washings  of  the  upper  soils — or  it  must  obtain  from 
abundant  sea-spray  a  sufficiency  to  supply  the  wants  of  the 
plants  that  grow  upon  it. 

The  practical  man  will  readily  acknowledge  that,  when  a  suffi- 
ciency of  saline  matter  is  not  conveyed  to  his  land  from  these 
or  similar  sources,  he  must  necessarily  supply  it  by  art.  He 
will  understand,  also,  that  the  saline  manures  he  adds  to  the  soil 
operate  by  yielding  to  the  plant  what  it  could  not  otherwise  so 
readily  obtain  ;  and  that  a  saline  substance  which  has  been 
found  to  benefit  his  neighbor's  land,  may  happen,  when  applied, 
to  do  no  good  to  his  own — because  his  own  may  already  con- 
tain a  sufficient  supply  of  that  substance. 

SECTION   II. — MODE  OF  DETERMINING  THE  LOCAL  VALUE  OF  SALINE 
MANURES. 

In  order,  therefore,  to  determine  whether  his  land  will  rea- 
dily be  benefited  by  the  application  of  those  saline  substances 
from  which,  in  other  districts,  or  upon  other  soils,  much  benefit 
has  been  derived,  the  intelligent  farmer  will  commence  a  series 
of  preliminary  trials  or  small  experiments. 

That  many  of  the  saline  substances  described  in  the  preced- 
ing Sections  may  be  profitably  applied  to  most  soils  by  the  prac- 


288  VALUE   OF   SALINE  MANURES. 

tical  farmer,  can  no  longer  be  doubted.  At  tie  same  time,  n* 
prudent  man  will  at  once  expend  any  large  sum  upcn  them 
until  either  he  himself,  or  some  of  his  immediate  neighbors  whf 
cultivate  a  similar  soil,  have  previously  proved  their  eflficacy  on 
a  smaller  scale.  It  is  no  doubt  the  duty  of  every  practical 
farmer — a  duty  he  owes  not  only  to  his  country  but  to  himself 
— to  be  alive  to  the  benefits  which  are  to  be  derived  from  every 
improved  method  of  culture  that  may  be  introduced  ;  but  it  is 
no  less  his  duty  to  avoid  every  reasonable  risk  of  pecuniary 
loss  which  might  be  injurious  to  himself. 

Suppose,  therefore,  I  were  to  enter  upon  a  farm  which  I  was 
desirous  of  rendering  as  productive  as  possible,  by  the  applica- 
tion of  every  new  manure,  or  every  new  method  of  culture  that 
might  prove  to  be  suited  to  the  kind  of  soil  I  possessed,  I 
would  begin  by  trying  the  effect  of  each  manure  or  method 
upon  a  single  acre,  and  I  would  extend  my  trials  or  alter  my 
methods  according  to  the  success  I  met  with. 

Among  saline  manures,  for  example,  I  would  try  nitrate  of 
soda,  or  carbonate  of  soda,  or  wood  ashes,  or  sulphate  of  soda,  or 
common  salt,  or  silicate  of  soda,  or  gypsum,  or  sulphated  urine,  or 
guano,  or  the  ammoniacal  salts,  or  the  soluble  phosphates,  or  a 
mixture  of  two  or  more  of  these  substances,  on  a  single  acre  or 
half  acre  of  my  various  crops — TiKcer  expending  in  this  way,  during 
any  one  year,  more  than  I  could  easily  afford  to  lose  if  my  trials 
shovM  fail ;  and  I  would  not  begin  to  use  any  of  these  sub- 
stances largely  till  I  was  satisfied  that  there  was  a  reasonable 
prospect  of  remuneration.  And  having  once  begun  u.pon  this 
assurance,  I  would  cease  applying  them  for  a  while  as  soon  as 
the  crops  no  longer  gave  me  a  fair  return  for  my  outlay — the 
probability  then  being,  that  the  soil  for  the  present  had  ob- 
tained enough  of  the  peculiar  substance  I  had  been  employing, 
and  stood  more  in  need  of  some  other. 

Thus  if,  as  happened  to  a  friend  of  mine,  a  dressing  of  salt 
was  followed  by  a  produce  of  35  bushels  from  the  first  wheat 
crop,  and  yet,  when  applied  to  the  next  crop  of  the  same  grain 


CIRCUMSTANCES   NECESSARY  TO    SDCCESS.  239 

on  the  same  field,  the  yield  was  only  20  bushels,  I  should  con- 
clude that,  for  the  present,  my  land  was  sufficiently  salted,  and 
that  I  had  better  apply  something  else,  I  would  therefore 
begin  my  experiments  anew  upon  my  salted  land,  I  would  try 
some  of  the  other  substances  above  named,  employing  always 
the  same  caution  and  economy  as  before,  and  carefully  keeping 
an  account  of  my  procedure,  and  of  my  profit  and  loss  from 
each  experiment. 

Such  facts,  also,  as  that  in  the  State  of  New  York,  after  a 
long-continued  use  of  gypsum,  th^  employment  of  leached  or  ex- 
hausted wood  ashes  (p,  233)  was  found  to  be  more  beneficial, 
would  incline  me  to  make  many  trials  of  such  variations  or  ro- 
tations of  manures. 

I  should  thus  have  always  several  experunental  patches  upon 
my  farm  ;  and  I  should  not  only  avoid  the  risk  of  serious  disap- 
pointment and  pecuniary  loss,  but  I  should  enliven  my  ordinary 
farm  routine  by  the  interest  I  should  necessarily  feel  in  watch- 
ing the  results  of  my  different  experiments — I  should  gradually 
acquire  habits  of  reflection,  and  of  careful  observation  also, 
which  would  be  of  the  greatest  possible  service  to  me  in  all  my 
future  operations.* 

SECTION    III. — OF   THE    CIRCUMSTANCES    WHICH   ARE  NECESSARY  TO 
INSURE  THE  SUCCESSFUL  APPLICATION  OF  SALINE  MANURES. 

The  application  of  saline  substances  to  the  soil  is  not  always 
attended  with  sensible  benefit  to  the  crop.  The  same  substance 
which,  in  one  district,  or  in  one  season,  has  produced  an  increased 
return,  may  fail  in  another  district  or  in  a  difierent  season.  The 
circumstances  which  are  necessary  to  insure  success  in  the  appli- 
cation of  saline  manures  are  chiefly  the  following  : — 

1°.  They  must  contain  one  or  more  of  those  substances  which 

*  For  numerous  suggestions  as  to  such  experiments,  I  would  refer  the 
reader  to  my  published  Experimental  Agriculture — a  work  entirely  devoted 
to  the  subject  of  rural  experiments. 


240  SUBSTANCES   EXERCISE   A   SPECIAL  ACTION 

are  necessary  to  the  growth  of  the  plant,  and  in  a  condition  or 
state  of  combination  in  which  the  plant  can  take  them  up. 

2°.  The  soil  must  be  more  or  less  deficient  in  these  substances. 

3".  The  weather  and  soil  must  be  moist  enough  to  admit  of 
their  being  readily  dissolved  and  conveyed  to  the  roots,  or  the 
land  must  be  artificially  irrigated. 

4°,  They  must  not  be  applied  in  too  large  a  quantity,  or 
allowed  to  come  in  contact  with  the  young  shoots  in  too  con- 
centrated a  form.  The  water  that  reaches  the  roots  or  young 
leaves  must  never  be  too  strongly  impregnated  with  the  salt,  or, 
if  the  weather  be  dry,  the  plant  will  be  blighted  or  burned  up. 

5".  The  soil  must  be  suflSciently  light  to  permit  the  salt  easily 
to  penetrate  to  the  roots,  and  yet  not  so  open  as  to  allow  it  to 
be  readily  washed  away  by  the  rains.  In  reference  to  this 
point  the  nature  of  the  subsoil  is  of  much  importance.  A  re- 
tentive subsoil  will  prevent  the  total  escape  of  that  which 
readily  passes  through  a  sandy  or  gravelly  soil ;  while  a  very 
open  subsoil,  again,  may  retain  little  or  nothing  of  what  has 
once  made  its  way  through  the  surface. 

6°.  I  may  add,  lastly,  that  it  is-  in  poor  or  worn-out  soils  that 
all  such  applications  may  be  expected  to  produce  the  most 
marked  and  characteristic  eflfects, 

BECTION   IV. OF   SALINE   MANURES  WHICH   EXERCISE  A   SPECUL  OB 

SPECIFIC  ACTION  UPON  PLANTS. 

An  interesting  branch  of  the  present  part  of  our  subject  is 
the  use  of  what  are  called  special  manures.  Certain  substances 
have  been  observed  to  exercise  a  special  action. 

1.  Upon  all  plants. — Thus,  the  salts  of  ammonia  promote 
the  growth,  or  prolong  the  green  and  growing  state  of  most 
plants.  Nitrate  of  soda  has  a  similar  effect — while  the  addition 
of  lime  to  the  soil,  especially  in  well-drained  and  high  lands, 
almost  uniformly  hastens  the  ripening  of  the  seed,  and  producei 
an  earlier  harvest. 


ON  DIFFERENT   KINDS   AND   PARTS    OF   PLANTS.  241 

2.  On  particular  parts  of  plants ; — as  when  the  gardener 
improves  his  roses  by  mixing  manganese  with  the  soil,  reddens 
his  ornamental  hyacinths  by  putting  carbonate  of  soda  into  the 
water  in  which  they  grow — or  by  other  substances,  as  by  the 
add  or  swjjcr-phosphate  of  soda,  attempts  to  vary  the  hue  or 
bloom  of  his  cultivated  flowers.  This  principle  is  attended  to 
in  practical  agriculture,  when  substances  are  mixed  with  the 
manure,  which  are  believed  to  be  specially  required  by  the  stalk 
of  corn,  where  a  field  produces  a  defective  straw — or  by  the 
ear,  where  the  grain  refuses  to  fill.  The  application  of  silicate 
of  potash,  of  soda,  or  of  lime,  to  the  soil  may  add  strength  to 
the  straw,  while  the  phosphates  fill  the  ear,  or  bring  it  to  ear- 
lier maturity — as  carbonate  of  potash,  according  to  Wolfi",  pro- 
motes the  growth  of  the  leaves  and  stems  of  the  vine,  while  the 
phosphates  develop  the  fruit. 

3.  On  particular  kinds  of  plants. — ^Farmyard  manure  rarely 
comes  amiss  to  any  soil  or  any  crop;  but  gypsum  exercises  a 
peculiar  action  upon  red  clover;  while  wood-ashes,  lime,  and 
other  alkaline  manures,  cause  white  clover  to  spring  up  sponta- 
neously, where  it  had  before  refused  to  grow  even  when  sown. 
So  lixiviated  wood  ashes  are  favorable  to  cats;  ammonia,  or 
the  nitrates,  are  by  some  regarded  as  the  peculiar  manures  for 
wheat;  phosphate  of  magnesia  has  been  extolled  as  a  specific 
for  potatoes  ;  and  superphosphate  of  lime  for  our  British  turnip 
crops. 

All  such  facts  as  these  are  exceedingly  valuable.  Many  of 
the  alleged  specifics,  however,  are  only  locally  so.  Thus  bones, 
which  produce  such  wonderful  effects  in  Great  Britain,  espe- 
cially upon  turnips  and  upon  some  old  grass  lands,  as  those  of 
Cheshire,  are  much  less  conspicuously  effective  in  some  parts  of 
Germany,  and  even  of  our  own  island  ;*  while  gypsum,  so 
much  and  so  generally  prized  by  the  German  and  American 
farmer,  is  more  rarely  found  to  answer  the  expectations  of  the 
English  agriculturist. 

*  On  some  of  the  soils  of  the  green-sand,  fbr  example. 
11 


84S  BESULTS   OF   EXPERIMEMS 

The  truth  is,  that  if  the  crop  we  wish  to  raise  specially  re« 
quires  any  one  substance  which  is  not  present  in  sufficient  quan- 
tity in  the  soil,  that  substance  will  there  prove  a  specific  for 
that  crop  ;  while,  in  another  soil  in  which  it  is  already  abun- 
dantly present,  this  substance  will  produce  little  beneficial  ef- 
fect. Failures,  therefore,  may  every  now  and  then  be  expect- 
ed in  the  use  of  so-called  specific  manures,  the  evil  of  which  is 
not  limited  to  the  immediate  loss  experienced  by  the  incau- 
tious experimenter.  They  serve  also  to  dishearten  those  who, 
through  their  much  faith,  have  been  disappointed  in  their  ex- 
pectations, and  thus  to  retard  the  progress  of  a  truly  rational 
experimental  agriculture. 

SECTION  V. RESULTS  OF  EXPERIMENTS  WITH  MIXED  SALINE  MA- 
NURES, MADE  WITH  THE  VIEW  OP  INCREASING  THE  QUANTITY  OF 
THE   CROP. 

The  same  remark  applies  also  to  artificial  mixed  manures, 
when  held  forth  as  specifics  for  any  or  for  all  crops  on  every 
soil.  The  animal  and  vegetable  manures  which  occur  in  na- 
ture, are  all  mixtures  of  a  considerable  number  of  different 
substances,  organic  and  inorganic.  We  are  imitating  na- 
ture therefore,  and  are  in  reality  so  far  on  the  right  road, 
when  we  compound  our  artificial  mixtures.  The  soil  may  be 
deficient  in  two,  three  or  more  substances  ;  and  to  render  it 
fertile,  it  may  be  necessary  to  add  all  these  ;  while,  if  it  be  de- 
fective in  one  only,  we  are  more  likely  to  administer  the  right 
one,  if  we  add  a  mixture  of  several  at  the  same  time.  It  is 
safer  and  surer,  therefore,  to  add  a  mixture  of  several  saline 
substances  to  our  soils. 

There  are  only  two  ways,  however,  in  which  we  can  safely 
make  up  mixtures  that  are  likely  to  be  useful — either  by  actual 
experiment  upon  the  kind  of  land  we  wish  to  improve,  or  by  an 
exact  imitation  of  the  procedure,  and  by  attention  to  the  re- 
quirements, of  nature. 


"WITH   MIXED   SALINE   MANTTRKS.  243 

1.  Mixhtre  of  nitrate  with  sulphate  of  soda. — In  1840  I  re- 
commended the  trial  of  sulphate  of  soda  (Glauber's  salts)  as  a 
manure,  and  in  1841,  Mr.  Fleming  of  Barochan,  besides  mak- 
ing an  experiment  with  the  sulphate  alone,  tried  a  mixture  of  it 
with  nitrate  of  soda  in  equal  weights' — adding  1^  cwt,  of  the 
mixture  to  the  acre.  The  effect  of  this  mixture  as  a  top-dress- 
ing upon  potatoes  was  extraordinary.  The  stems  were  six  and 
seven  feet  in  length,  and  the  produce  upward  of  30  tons  per  impe- 
rial acre.  In  1842,  tried  on  a  larger  scale,  the  produce  was 
not  so  extraordinary  ;  but,  though  a  very  dry  season,  the  pro- 
duce was  18  tons  per  acre  of  early  American  potatoes  ;  while 
the  dung  alone,  40  cubic  yards  per  acre,  gave  less  than  13  tons. 
These  results  are  sufficiently  striking  to  justify  the  reader  in 
trying  this  mixture  on  any  soil.  If  his  fields  be  like  the  land 
of  Mr.  Fleming,  the  trial  may  prove  eminently  successful ;  if 
different  in  physical  character  or  chemical  composition,  or  if 
the  season  be  unpropitious,  the  result  may  be  less  favorable. 
A  mixture,  though  it  succeed  in  the  hands  of  fifty  experiment- 
ers, will  still  not  be  entitled  to  be  considered  as  a  specific.  It 
must  first  be  found  never  to  fail. 

The  cost  of  this  mixture,  as  applied  per  acre,  was  at  that 
time  as  follows  : — 

75  lb.  nitrate  of  soda,  at  22s.  per  cwt.      .        .        .        £0  14  9 
*ih  lb.  dry  (uncrystallised)  sulphate  of  soda,  at  93.,  0    6  3 

[about  $5  25]        110 

The  increased  produce  from  this  application — strewed  about 
the  young  plants  when  they  came  above  ground — was  8  tons 
per  acre  in  1841,  and  5  tons  per  acre  in  1842. 

2.  The  superior  effect  of  mixtures  above  that  of  the  substances 
they  contain  when  employed  singly,  is  shown  in  an  interesting 
manner  by  the  following  results,  obtained  by  the  same  experi- 
menter : — 

An  entire  field  was  manured  for  potatoes  with  40  cubic  yards 


244  MIXED   SULPHATES   AND  NITRATES. 

of  dung,  and  when  the  potatoes — early  Americans — ^were  a  few 
inches  above  the  ground,  different  measured  portions  of  the 
field  were  top-dressed  with  diiTerent  saline  substances,  with  the 
following  results  per  imperial  acre  : — 

Tons. 

Dung  alone  gave  ....         12| 

. .    with  2    cwt.  sulphate  of  soda,  '   .  .         12| 

1  k  cwt.  nitrate  of  soda,      .  .  .         16 


Ij  cwt.  sulphate,    )   ^^  ,  ^g 

I  cwt.  nitrate,       )  "^^'="> 


Here,  though  the  sulphate  alone  produced  no  increase,  it 
materially  augmented  the  effect  of  the  nitrate  when  the  two 
were  applied  together. 

3.  Sulphate  of  soda  with  sulphate  of  ammonia. — Again,  on 
the  same  field  on  which  sulphate  of  soda,  applied  alone,  gave 
no  increase, 

Tons. 

1 J  cwt.  sulphate  of  ammonia  alone  gave  only    .    14i 

While  1 1  cwt.  sulphate  of  soda  and  |     .     •,  ,03 

I  cwt  sulphate  of  ammonia,}"^^^^^^^®      •    ^^^ 

Being  an  increase  of  6  tons  an  acre  above  sulphate  of  soda, 
and  4  tons  above  sulphate  of  ammonia  applied  alone. 

4.  Nitrate  of  soda  with  sulphate  of  magnesia. — Also  on  the 
same  field,  while 

Tons. 
IJ  cwt.  of  nitrate  of  soda  gave,  as  above,  only    .    16 
And  li  cwt.  of  sulphate  of  magnesia,  only      .  .     13^ 

1   cwt.  of  each,  mixed  together,  gave     .  .    22  J 

Thus  experiment,  as  well  as  theory,  indicates  that  the  appli- 
cation of  several  saline  substa/nces  mixed  together,  is  more  likely  to 
increase  the  produce  of  the  soil  than  a  larger  addition  of  either 
applied  alone. 

6.  Phosphate  of  magnesia  with  phosphate  of  ammonia. — I  have 
Baid  that  attention  to  the  requirements  of  nature  will  indicate 


EXPERIMENTS  WITH  MIXED  PHOSPHATES.  245 

what  mixtures  may  be  tried  with  the  hope  of  success,  and  even 
what  mixtures  may  be  likely  to  prove  specific  manures.  Thus 
it  is  known  from  analysis  that  the  seeds  of  plants — the  grain  of 
our  corn  crops  for  example — contain  much  nitrogen  in  their 
gluten,  and  that  the  ash  of  grain  is  rich  in  phosphoric  acid  and 
magnesia.  It  was  natural  to  suppose,  therefore,  that  the  appli- 
cation to  growing  corn  of  a  mixture  capable  of  specially  sup- 
plying these  three  substances  would  specially  act  in  filUng  the 
ear.  A  saline  compound  known  by  the  name  of  phosphate  of 
magnesia  and  ammonia,  containing  the  two  phosphates  united,* 
is  fitted  for  this  purpose,  and  was  consequently  recommended 
for  trial. 

Experiments,  recently  made,  show  that  it  exercises  a  power- 
ful influence,  especially  upon  Indian  corn.  Applied  at  the  rate 
of  130  to  260  lb.  per  acre,  it  had  also  a  very  favorable,  though 
less  marked,  influence  upon  wheat.  Upon  Indian  corn,  at  the 
rate  of  3  cwt.  per  acre,  it  increased  the  crop  of  grain  six  times, 
and  of  straw  three  times.  A  constant  effect  is  to  increase  the 
weight  of  the  grain  per  bushel  as  common  salt  does;  and,  like 
many  other  substances,  it  produces  most  marked  eflfects  upon 
poor  and  worn-out  soils. 

This  compound,  therefore,  is  deserving  of  further  trial ;  and 
it  is  desirable  that  attempts  should  be  made  to  manufacture  it 
for  the  manure-market  at  a  moderate  price.f 

SECTION  VI. ^RESULTS  OP  EXPERIMENTS  WITH  MIXED  SALINE  MA- 
NURES MADE  WITH  THE  VIEW  OP  APFECTINO  THE  CHARACTER  OR 
QUALITY  OP  THE  CROP. 

The  above  are  illustrations  of  the  kind  of  mixtures  which,  on 

*  It  is  prepared  by  pouring  mixed  solutions  of  sulphate  of  magnesia  and 
sulphate  of  ammonia  into  a  solution  of  the  common  phosphate  of  soda  of 
the  shops. 

f  See  the  Author's  Experimental  Chemistry,  p.  216.  Also  the  Annaka 
de  Ohemie  for  September  1852,  p.  46. 


S46  MIXTURES   PROMOTING   GROWTH 

the  faith  of  results  obtained  by  actual  trial,  may  be  recom- 
mended to  the  practical  man  as  likely  to  increase  the  quantity 
of  the  crop.  But  mixtures  may,  by  the  reflecting  farmer,  be 
applied  for  other  purposes. 

1.  As  when  he  mixes  together 

Nitrate  of  Soda, 3  cwt  ) 

Gypsum, 5    "J-  28  cwt 

"Wood  ashes, 20    "     ) 

and  applies  this  mixture  at  the  rate  of  5  or  6  cwt.  an  imperial 
acre  as  a  cure  for  clover-sick  land — as  recommended  by  Mr. 
Prideaux. 

2.  Or  when  two  good  effects  on  the  growth  are  sought  for 
at  the  same  time  by  the  simultaneous  application  of  two  sub- 
stances to  the  crop.  Or  when  an  evil  effect,  considered  likely 
to  follow  from  the  use  of  one  substance  alone,  is  to  be  pre- 
vented or  counteracted  by  the  use  of  another  substance  along 
with  it. 

Thus,  nitrate  of  soda  applied  to  corn  crops  gives  increased 
luxuriance,  and  greatly  promotes  the  growth  of  straw,  while  it 
also  increases  the  size  of  the  ear.  But  this  rapid  growth  makes 
wheat,  in  some  localities,  liable  to  mildew.  It  is  apt  also  to 
give  a  feebleness  to  the  straw,  which  makes  the  crop  more 
liable  to  be  laid  by  the  wind  and  rains  ;  so  that  if  stormy  wea- 
ther come  when  harvest  approaches,  the  corn  may  be  seriously 
damaged.  On  the  other  hand,  common  salt,  while  it  usually 
strengthens  and  brightens  the  straw,  makes  mildew  more  rare, 
and  adds,  besides,  to  the  weight  of  the  grain  per  bushel.  By 
using  the  two  substances  together,  therefore,  the  increased 
growth  caused  by  the  nitrate  will  be  secured,  and  mildew  pro- 
bably prevented ;  while  the  common  salt  will  give  the  straw 
strength  to  stand.  With  this  view  experiments  have  been  made 
with  such  a  mixture  by  various  persons,  with  the  best  results. 
I  quote  only  two  results,  obtained  at  Holkham  by  Mr.  Keary, 
&om  applications  to  his  wheat  crops  in  1350  and  1851. 


AND   PBEVENTINO   MILDEW.  247 


Application 

Prodi 

ace. 

per  imperial  acre. 

Grain. 

Straw. 

1860.  No  application, 

37  bush. 

26  cwt. 

Nitrate  of  soda,  1  owt.    . 

40    .. 

32  .. 

Nitrate  of  soda,  1    . . 
Common  salt,     2    . .  )    ' 

40    . . 

34 

In  this  case  the  addition  of  salt  produced  no  increase  above 
the  nitrate  alone,  except  in  augmenting  by  2  cwt.  the  weight  of 
the  straw. 

1851.  No  application,        .  .  .  31  i  bush.  27  cwt 

Nitrate  of  soda,  1  cwt,  .  .  43i    ..  31    .. 

Nitrate  of  soda,  1  •  •  |.  4k  i  og* 

Common  salt,     2   . .  J  *  *  3    •  • 

In  this  experiment  the  grain  was  increased  nearly  2  bushels 
by  the  salt,  while  the  straw  was  lessened  by  1  cwt.  These 
diflferences  are  of  little  pecuniary  consequence.  The  chief  ad- 
vantage to  be  looked  for  from  the  use  of  the  salt  is,  as  I  have 
said,  in  its  making  more  sure  the  gain  which  nitrate  of  soda,  on 
all  poor  soils,  and  especially  upon  sickly  crops,  may  be  expected 
to  produce. 

SECTION   VII. — ^USE    OP    ARTIFICIAL    MIXED    MANURES,    COMPOUNDED 
IN   IMITATION    OP    NATURAL   MANURES ARTIFICIAL   GUANOS. 

The  above  experiments  illustrate  how  saline  mixtures  may 
be  made  and  used  for  a  definite  and  known  purpose,  other  than 
that  of  simply  adding  to  the  natural  produce  of  the  land.  But 
mixtures  may  also  be  made,  with  the  view  of  imitating  nature, 
and  of  compounding  by  art  those  valuable  manures  which  she 
furnishes  in  such  variety,  where  we  can  do  it  efifectually,  and  at 
a  reasonable  cost. 

Thus  guano  is  a  highly  fertilising  substance;  and  as  the  sup- 
ply brought  to  this  country  is  limited,  and  the  price  at  which  it 
was  sold,  when  first  introduced  into  this  country,  was  a  great 

♦  Journal  of  the  Royal  Agricultural  Society,  vol.  xiiL  p.  210.  See  also 
for  similar  experiments  by  Mr.  Pusey,  vol.  xiL  p.  202. 


248  ARTIFICIAL   GUANOS. 

bar  to  its  extensive  employment,  I  was  induced  at  the  time  to 
recommend  the  following,  or  some  similar  mixture — as  likely  to 
resemble  it  in  fertilising  virtue,  because  it  contains  the  same  in- 
gredients, as  determined  by  analysis — to  be  inexhaustible  in 
supply,  because  prepared  chiefly  from  the  produce  of  our  own 
manufactories — and  to  be  at  least  as  cheap  as  the  best  import- 
ed guano. 

315  lb.  (7  bushels)  of  bone  dust  at  2s.  9d.  a  bushel,  £0  19  0  [$4  15 

100  "  sulphate  of  ammonia,        .        ,        .        .       0  14  6  3  63 

20  "  of  pearl  ash,  or  801b.  of  wood  ashes,        .      0    40  1  00 

80   "  of  common  salt, 0     16  0  37 

20  "  of  dry  sulphate  of  soda,     .        .        .        .020  0  50 

25    "  of  nitrate  of  soda, 0     5  0  1  25 

50  "  of  crude  sulphate  of  magnesia,  .        .        .016  038 


610  £2     7  6     $11  88 

This  quantity  should  be  equal  in  efficacy  to  4  or  5  cwt.  of 
guano,  and  may  by  many  be  made  at  a  cheaper  rate. 

This  recipe  has  formed  the  basis  of  numerous  varieties  of  ar- 
tificial guano  which  have  been  manufactured  in  diiferent  parts 
of  the  country,  and  sold  under  different  names,  and  at  various 
prices — some  of  them  sufificiehtly  low  to  indicate  that  either  the 
mixtures  are  not  good,  or  that  they  are  not  made  of  valuable 
materials.  They  have,  therefore,  been  applied  to  the  land  with, 
as  might  be  expected,  very  discordant  results. 

Though  we  should  never  be  able  to  manufacture  an  artificial 
guano  equal  to  the  native,  this  good  effect  to  the  practical  man 
arose  at  once  from  the  publication  of  the  above  recipe,  and  from 
the  manufacture  and  sale  of  artificial  guano — that  natural  guano 
fell  remarkably  in  price,  and  with  it  rape-dust,  bone-dust,  and 
other  costly  manures  of  a  similar  kind.  Thus  chemistry  pos- 
sesses an  intelligible  money  value  even  to  the  working  farmer. 

This  question  of  cheapness  is  second  only  to  that  of  eflSciency 
in  a  manure.  To  make  these  manures  cheap  is  the  next  point 
after  making  them  well.  "With  many  manufacturers — and  un- 
fortunately with  many  purchasers  too — cheapness  is  made  the 


CHEAPNESS   SECOND   ONLY  TO   EFFICIENCY,  249 

first  consideration;  and  hence  mixtures  are  brought  into  the 
market  at  a  low  price,  which  are  of  comparatively  little  value, 
and  can  produce  a  sensibly  profitable  result  in  a  few  cases  only, 
and  upon  peculiar  soils. 

To  make  the  manure  cheap,  the  ingredients  employed  must 
be  so.  The  refuse  of  manufactories  has  been  looked  to  as  a 
source  of  such  cheap  materials,  and  not  without  the  prospect  of 
ultimate  advantage  to  the  country.  The  use  of  such  refuse, 
however,  has,  in  the  first  instance,  led  to  much  imposition.  The 
exact  nature  of  the  refuse  must  be  known,  and  its  uniformity 
and  constancy  of  composition  ascertained,  before  it  can  be  safe* 
ly  employed  in  the  manufacture  of  any  mixed  manure. 

It  is  a  great  objection  to  the  numerous  artificial  guanos  and 
mixed  manures  now  offered  for  sale,  that  the  public  have  no 
guarantee,  either  of  the  competency  of  the  parties  who  make 
them  to  devise  a  mixture  which  shall  be  universally  advanta- 
geous— of  their  ability  to  select  materials  which  shall  render 
it  of  that  uniform  composition  which  is  essential  to  its  success 
— or  of  their  good  faith  in  endeavoring  to  secure  such  a  compo- 
sition.* 

*For  numerous  recipes  for  particular  crops,  the  reader  is  referred  to  the 
author's  Lectures,  2d  edit'on,  p.  639-646. 


CHAPTER  XIX. 

Uae  of  lime  in  Agrlculbire. — Composition  of  limestones,  chalks,  corals, 
shell-sands,  and  marls. — Burning  and  slaking  of  lime,  hydrate  of  lime, 
spontaneously  slaked  lime. — Effects  of  exposure  to  the  air  upon  quick- 
lime.— Advantages  of  burning  lime  partly  mechanical  and  partly  chemi- 
cal.— Silicate  of  lime  produced  by  burning. — Quantity  of  lime  usually 
applied  to  the  land. — Visible  improvements  produced  by  lime. — Why 
liming  must  be  repeated. — How  lime  is  gradually  removed  from  the  land. 
—Circumstances  which  modify  the  effects  of  lime  upon  the  land. — Che- 
mical effects  of  caustic  and  of  mild  lime  upon  the  soil. — What  is  meant 
by  overliming. — Proportion  of  lime  in  overlimed  land. — How  overtiming 
is  to  be  remedied. — Exhausting  effects  of  lime. — Is  lime  necessarily  ex- 
hausting. 

The  use  of  lime  is  of  the  greatest  importance  in  practical 
agriculture.  It  has  been  employed  in  the  forms  of  marl,  shell, 
shell-sand,  coral,  chalk,  limestone,  limestone  gravel,  quick-lime, 
&c.,  in  almost  every  country,  and  from  the  most  remote  period. 

SBCrnON   I. COMPOSITION   OF   LIMESTONES   AND   CHALKS. 

When  diluted  muriatic  acid,  or  strong 
vinegar,  is  poured  upon  pieces  of  lime- 
stone, chalk,  common  soda,  or  common 
pearl  ash,  effervescence  takes  place,  and 
carbonic  acid  gas  is  given  off,  (p.  18.) 
If  a  current  of  this  gas  be  made  to  pass 
througl\  lime  water,  (see  figure,)  the 
liquid  becomes  milky,  and  a  white  pow- 
der falls,  which  is  pure  carbonate  of  lime. 
It  consists  of 


COMPOSITION   OP   IJMESTONES.  251 

Per  cent. 

Carbonic  acid, 43-7 

Lime.  66*3 

100 
One  ton  of  pure  dry  carbonate  of  lime  contains,  of 

Cwta. 

Carbonic  acid, 8| 

Lime. Hi 

20 

Limestone  and  chalk  consist,  for  the  most  part,  of  carbonate 
of  lime.  In  soft  chalk,  the  particles  are  held  more  loosely  to- 
gether; in  the  hard  chalks  and  in  limestones,  the  minute  grains 
have  been  pressed  or  otherwise  brought  more  closely  together, 
so  as  to  form  a  more  solid  and  compact  mass. 

In  regard  to  limestones  and  chalks,  there  are  several  circum- 
stances which  it  is  of  importance  for  the  practical  man  to  know. 
For  example — 

a.  That  they  are  not  composed  entirely  of  mineral  or  inor- 
ganic particles,  such  as  are  formed  by  the  passage  of  a  current 
of  carbonic  acid  through  lime-water.  They  consist  in  great 
part,  sometimes  almost  entirely,  of  minute  microscopic  shells, 
of  the  fragments  of  shells  of  larger  size,  or  of  solidified  masses 
of  corals,  which  formed  coral  reefs  in  ancient  seas  which  once 
covered  the  surface  where  the  limestones  are  now  met  with. 
The  blue  mountain  limestones  contain  many  of  these  coral  reefs, 
while  in  our  chalk  rocks  vast  quantities  of  microscopic  shells 
and  fragments  of  shells  appear. 

b.  Being  thus  formed  at  the  bottom  of  masses  of  moving  wa- 
ter, the  chalks  and  limestones  are  seldom  free  from  a  sensible 
admixture  of  sand  and  earthy  matter.  Hence,  when  they  are 
treated  with  diluted  acid,  though  the  greater  part  dissolves 
and  disappears,  yet  a  variable  proportion  of  earthy  matter  al- 
ways remains  behind  in  an  insoluble  state.    This  earthy  matter 


253  "  PHOSPHATE    OF   LIME    IN   LIMESTONE. 

is  sometimes  less  than  half  a  per  cent  of  the  whole  weight, 
though  sometimes  it  amounts  to  as  much  as  30  or  40  per  cent. 

<;.  All  animals  hitherto  examined  contain  in  the  parts  of  their 
bodies  traces  more  or  less  distinct  of  phosphoric  acid,  generally 
in  combination  with  lime,  forming  phosphate  of  lime.  This  phos- 
phate of  lime  their  remains,  when  dead,  retain  in  whole  or  in 
part.  It  thus  happens  that  limestones  almost  invariably  con- 
tain phosphoric  acid,  and  that  the  proportion  of  it  usually  in- 
creases with  that  of  the  visible  remains  of  animals,  shells,  co- 
rals, &c.,  which  occur  in  it.  In  the  magnesian  limestones  of  the 
county  of  Durham,  I  have  found  the  proportion  of  phosphate  of 
lime  to  be  as  small  as  0.01  to  0.15  per  cent  ;  while  in  a  lime- 
stone from  Lanarkshire  (Carluke,)  analysed  in  my  laboratory, 
it  amounted  to  IJ  per  cent  ;  or  one  hundred  pounds  of  the 
burned  lime  contained  as  much  as  2^  pounds  of  phosphate  of 
lime. 

d.  The  parts  of  animals  also  contain  sulphur,  and  this  has 
given  rise  to  the  presence  of  sulphuric  acid  in  chalks  and  lime- 
stones. This  acid  exists  in  them  in  combination  with  lime — ^in 
the  state  of  gypsum.  The  proportion  of  this  gypsum  which  I 
have  hitherto  found  in  native  chalks  and  limestones  is  small, 
varying  from  one-third  to  four-fifths  of  a  per  cent. 

c.  Carbonate  of  magnesia,  the  common  magnesia  of  the  shops, 
is  also  present,  almost  invariably,  in  all  our  limestone  and  chalk 
rocks.  In  the  purest  it  forms  1  or  2  per  cent,  in  the  most  im- 
pure from  40  to  45  per  cent  of  the  whole  weight.  The  rocks 
called  dolomites  or  magnesian  limestones,  (p.  97,)  are  charac- 
terised by  the  presence  of  a  large  proportion  of  carbonate  of 
magnesia.  In  the  old  red  sandstone  formation  also,  beds  of 
limestone  occur  which  are  rich  in  magnesia.  Such  limestones 
are  usually  considered  less  valuable  for  agricultural  purposes. 
They  can  be  applied  less  freely  and  abundantly  to  the  land,  and 
possess  what  practical  men  call  a  burning  or  a  scorching  quali- 
ty.   They  are,  however,  preferred  to  purer  limes  in  some  dis 


CORALS,  SHELL  SANDS,  AND  MARLS,  253 

tricts,  as  in  the  high  lands  of  Galloway,  for  application  to  hill 
pastures 

SECTION   n. — COMPOSITION   OF   CORALS,    SHELL-SANDS,  AND   MARLS. 

1°.  Corals,  as  they  are  gathered  fresh  from  the  sea  on  the 
Irish  (Bantry  Bay)  and  other  coasts,  contain,  besides  carbonate 
of  lime,  a  small  percentage  of  phosphate  of  lime,  and  sometimes 
not  less  than  14  per  cent  of  animal  matter — (Jackson.)  This 
animal  matter  adds  considerably  to  the  fertilising  value  of  coral 
sand,  when  laid  upon  the  land  in  a  recent  state,  or  when  mado 
into  compost. 

2°.  Shdlrsand  consists  of  the  fragments  of  broken  shells  of 
various  sizes,  mixed  with  a  variable  proportion  of  sea  sand.  It 
contains  less  animal  matter  than  the  recent  corals,  and  its  value 
is  diminshed.by  the  admixture  of  sand,  which  varies  from  20  to 
10  per  cent  of  the  whole  weight.  On  the  shores  of  many  of 
the  Western  Islands,  shell-sand  is  found  in  large  quantities,  and 
is  extensively  and  beneficially  applied,  especially  to  the  hill-side 
pastures,  and  to  peaty  soils. 

3°.  Marls  consist  of  carbonate  of  lime — generally  the  frag- 
ments of  shells — mixed  with  sand,  clay  or  peat^  in  various  pro- 
portions. They  contain  from  5  to  as  much  as  80  or  90  per  cent 
of  carbonate  of  lime,  and  are  considered  more  or  less  rich  and 
valuable  for  agricultural  purposes  as  the  proportion  of  lime  in- 
creases. They  are  formed/ for  the  most  part,  from  accumula- 
tions of  shells  at  the  bottom  of  fresh-water. lakes  which  have 
gradually  been  filled  up  by  clay  or  sand,  or  by  the  growth  of 
peat. 

SECTION   III. — OF  THE   BURNING    AND    SLAKING   OF   LIME. 

1°.  Burning. — Limestones,  when  of  a  pure  variety,  consist 
almost  entirely  of  carbonate  of  lime.  This  carbonate  of  lime, 
as  we  have  seen,  contains  about  56  per  cent  of  lime,  or  11 J 
cwt.  to  the  ton. 


954  BURNING   AND   SLAKING    OF   LIUE. 

When  this  limestone  is  put  into  a  kiln,  with  so  much  coal  as, 
when  set  on  fire,  will  raise  it  to  a  sufficiently  high  temperature, 
the  carbonic  acid  is  driven  off  in  the  form  of  gas,  leaving  the 
pure  lime  behind. 

In  this  state  it  is  known  as  burned  lime,  lime-shells,  caustic 
lime,  and  quick  lime,  and  possesses  properties  very  different 
from  those  of  the  unburned  limestone.  It  has  a  hot  alkaline 
taste,  absorbs  water  with  great  rapidity,  falls  to  powder  or 
slakes,  and  finally  dissolves  in  132  times  its  weight  of  cold  water. 
This  solution  is  known  by  the  name  of  lime-water. 

2°.  Slaking. — Its  tendency  to  combine  chemically  with  water 
is  shown  in  the  process  of  slaking.  Almost  every  one  is  fami- 
liar with  the  fact  that,  when  water  is  poured  upon  quick-lime, 
it  heats,  emits  steam,  swells,  cracks,  and  at  last  falls  to  a  fine, 
usually  white,  powder,  which  is  two  or  three  times  as  bulky  as 
the  lime  in  its  unslaked  state.  "When  thus  fully  slaked  and 
cool,  the  fine  powder  consists  of — 

Lime, 76  per  ceut 

Water,    .  ...        24      . 

100 

Or  20  cwt.  of  pure  burned  lime  absorb  and  retain  in  the  solid 
state  6J  cwt.  of  water,  forming  26J  cwt.  of  slaked  lime,  called 
hydrate  of  lime  by  chemists. 

When  quick-lime  is  left  exposed,  to  the  air,  even  in  dry 
weather,  it  gradually  absorbs  moisture  from  the  atmosphere, 
and  falls  to  powder  without  the  artificial  addition  of  water. 
In  this  case,  however,  it  does  not  become  sensibly  hot  as  it  does 
when  it  is  slaked  rapidly  by  immersion,  or  by  pouring  water 
apoQ  it. 


SPONTANEOUS    SLAKING.  255 


SECTION    IV. OP   THE   CHANGES   WHICH     SLAKED     LIME    UNDERGOES 

BY    EXPOSURE   TO    THE    AIR,    AND    OF   THE    BENEFITS    OF   BURNING 
LIMESTONES. 

1°.  Effects  of  ex-posure  to  the  air. — When  lime  from  the  kiln 
is  slaked  by  means  of  water,  it  still  retains  its  quick  or  caustic 
quality.  But  if,  after  it  has  fallen  to  powder,  it  be  left  un- 
covered in  the  open  air,  it  gradually  absorbs  carbonic  acid  from 
the  atmosphere,  gives  off  its  water,  and  becomes  reconverted 
into  dry  carbonate  of  lime. 

When  lime  is  allowed  to  slake  spontaneously  in  the  air,  it 
first  absorbs  water,  and  slakes,  and  falls  to  powder,  and  then 
absorbs  carbonic  acid  and  is  changed  into  carbonate. 

But  as  soon  as  a  portion  of  the  lime  slakes,  it  begins  to  absorb 
carbonic  acid,  probably  long  before  the  whole  is  slaked.  Thus  the 
two  processes  go  on  together,  so  that,  in  lime  left  to  slake  sponta- 
neously, as  it  is  often  on  our  fields  and  headlands,  the  powder 
into  which  it  falls  consists  in  part  of  caustic  hydrate  and  in 
part  of  mild  carbonate  of  lime.  Its  composition  is  nearly  as 
follows: — 

Per  cent 
Carbonate  of  lime, 57.4 

Hydrate  of  lime.      |  ^"^^r,  ;  ^?;*  }         ...        42^ 

100 

When  it  reaches  this  stage  or  composition,  the  remainder  of 
the  hydrate  absorbs  carbonic  acid  much  more  slowly,  so  that 
when  spread  upon  or  mixed  with  the  soil,  it  takes  a  much  longer 
time  to  convert  it  into  carbonate.  At  last,  however,  after  a 
longer  or  shorter  period  of  time,  the  whole  of  the  lime  becomes 
saturated  with  carbonic  acid,  and  is  brought  back  to  the  same 
state  of  mild  ttn-caustic  carbonate  in  which  it  existed  in  the  nar 
tive  chalk  or  limestone  before  it  was  put  into  the  kiln. 


256  ADVANTAGES  OF  BURNING. 

2°.  Advantages  of  burning  lime. — If  the  lime  return  to  the 
same  chemical  state  of  carbonate  in  which  it  existed  in  the  state 
of  chalk  or  limestone, — what  is  the  benefit  of  burning  it  ? 

The  benefits  are  partly  mechanical  and  partly  chemical. 

a.  We  have  seen  that,  on  slaking,  the  burned  lime  falls  to  an 
exceedingly  fine  bulky  powder.  When  it  afterwards  becomes 
converted  into  carbonate,  it  still  retains  this  exceedingly  mi- 
nute state  of  division  ;  and  thus,  whether  as  caustic  hydrate  or 
as  mild  carbonate,  can  be  spread  over  a  large  surface,  and  be 
intimately  mixed  with  the  soil.  No  available  mechanical  means 
could  be  economically  employed  to  reduce  our  limestones,  or 
even  our  softer  chalks,  to  a  powder  of  equal  fineness. 

h.  By  burning,  the  lune  is  brought  into  a  caustic  state,  which 
it  retains,  as  we  have  seen,  for  a  longer  or  shorter  period,  till 
it  again  absorbs  carbonic  acid  from  the  air  or  from  the  soil. 
In  this  caustic  state,  its  action  upon  the  soil  and  upon  organic 
matter  is  more  energetic  than  in  the  state  of  mild  lime  ;  and 
thus  it  is  fitted  to  produce  efi'ects  which  mere  powdered  lime- 
stone or  chalk  could  not  bring  about  at  all,  or  to  produce  them 
more  effectually,  and  in  a  shorter  period  of  time. 

c.  Limestones  often  contain  sulphur  in  combination  with  iron, 
(iron  pyrites.)  The  coal  or  peat,  with  which  it  is  burned,  also 
contains  sulphur.  During  the  burning,  a  portion  of  this  sulphur 
unites  with  the  lime  to  form  gypsum,  by  this  means  adding  to 
the  proportion  of  this  substance,  which  naturally  exists  in  the 
limestone. 

d.  Earthy  and  silicious  matters  are  sometimes  present  in 
considerable  quantity  in  our  limestone  rocks.  When  burned 
in  the  kiln,  the  silica  of  this  earthy  matter  unites  with  lime  to 
form  silicate  of  lime.  This  silicate  of  lime,  being  diffused  through 
the  burned  and  slaked  lime,  and  afterwards  spread,  in  a  mi- 
nute state  of  division,  through  the  soil,  is  in  a  condition  in  which 
it  may  yield  silica  to  the  growing  plant. 

Thus  the  benefits  of  burning  are,  as  I  have  said,  partly  me- 
chanical and  partly  chemical.    They  are  mechanical,  inasmuch 


QUANTITY   OF   LIME   REQUIRED.  251 

as,  by  slaking,  the  burned  lime  can  be  reduced  to  a  mucb  finer 
and  more  bulky  powder  than  the  limestone  could  be  by  any  me- 
chanical means  ;  and  they  are  chemical,  inasmuch  as,  by  burn- 
ing, the  lime  is  brought  into  a  more  active  and  caustic  state, 
and  is,  at  the  same  time,  mixed  with  variable  proportions  of 
sulphate  and  of  silicate  of  lime — which  may  render  it  more 
useful  to  the  growing  crops. 

SECTION  V. QUANTITY   OP   LIME   USUALLY  APPLIED  TO   THE   LAND. 

The  quantity  of  quick-lime  laid  on  at  a  single  dressing,  and  the 
frequency  with  which  it  may  be  repeated,  depend  upon  the 
kind  of  land,  upon  the  depth  of  the  soil,  upon  the  quantity 
and  kind  of  vegetable  matter  which  the  soil  contains,  and  upon 
the  species  of  culture  to  which  it  is  subjected.  If  the  land  be 
wet,  or  badly  drained,  a  larger  application  is  necessary  to  pro- 
duce the  same  effect,  and  it  must  be  more  frequently  repeated. 
But  when  the  soil  is  thin,  a  smaller  addition  will  thoroughly 
impregnate  the  whole,  than  where  the  plough  usually  descends 
to  the  depth  of  8  or  10  inches.  On  old  pasture  lands,  where 
the  tender  grasses  live  in  2  or  3  inches  of  soil  only,  a  feeble 
dressing,  more  frequently  repeated,  appears  to  be  the  more  rea 
sonable  practice  ;  though  in  reclaiming  and  in  laying  down 
land  to  grass,  a  heavy  first  liming  is  often  indispensable. 

In  arable  culture,  larger  and  less  frequent  doses  are  admissi' 
ble,  both  because  the  soil  through  which  the  roots  penetrate 
must  necessarily  be  deeper,  and  because  the 'tendency  to  sink 
beyond  the  reach  of  the  roots  is  generally  counteracted  by  the 
frequent  turning  up  of  the  earth  by  the  plough.  Where  vege- 
table matter  abounds,  much  lime  may  be  usefully  added  ;  and 
on  stiff  clay  lands,  after  draining,  its  good  effects  are  very  re- 
markable. On  light  land,  chiefly  because  there  is  neither  moist- 
ure nor  vegetable  matter  present  in  sufficient  quantity,  very 
large  applications  of  lime  are  not  so  usual,  and  it  is  generally 
preferable  to  add  it  to  such  land  in  the  state  of  compost  only. 


i58  WHY  LIME  MUST  BE   REPEATED. 

The  largest  doses,  however,  which  are  applied  in  practice, 
alter  in  a  very  immaterial  degree  the  chemical  composition  of 
the  soil.  The  best  soils  generally  contain  a  natural  proportion 
of  lime,  not  fixed  in  quantity,  yet  scarcely  ever  wholly  wanting. 
But  an  ordinary  liming,  when  well  mixed  up  with  a  deep  soil, 
will  rarely  amount  to  ont  per  cent  of  its  entire  weight.  It  re- 
quires about  400  bushels  (12  to  15  tons)  of  burned  lime  per  acre 
to  add  one  per  cent  of  lime  to  a  soil  of  twelve  inches  in  depth. 
If  only  mixed  to  a  depth  of  six  inches,  this  quantity  would  add 
about  two  per  cent  to  the  soil. 

Though  the  form  in  which  lime  is  applied,  the  dose  laid  on,  and 
the  interval  between  the  doses  varies,  yet  in  Great  Britain,  at 
least  in  those  places  where  lime  can  be  obtained  at  a  reasonable 
rate,  the  quantity  applied  amounts,  on  an  average,  to  from  7  to 
10  bushels  a-year. 

SECTION  VI. — ^VISIBLE  IMPROVEMENTS   PRODUCED  BY   LIME,  AND 
WHY  LIMING  MUST  BE  REPEATED. 

The  most  remarkable  visible  alterations  produced  by  lime  are 
— upon  pastures,  a  greater  fineness,  sweetness,  closeness,  and 
nutritive  character  of  the  grasses — on  arable  lands,  the  im- 
provement in  the  texture  and  mellowness  of  stiff  clays,  the  more 
productive  crops,  their  better  quality,  and  the  earlier  period  at 
which  they  ripen,  compared  with  those  grown  upon  soils  to 
which  no  lime  has  ever  been  added. 

This  influence  of  lime  is  well  seen  when  limed  is'  compared 
with  unlimed  land,  or  when  soils,  which  are  naturally  rich  in 
lime,  are  compared  with  such  as  contain  but  little.-  Barley 
grown  on  the  former  is  of  better  malting  quality.  The  turnips 
of  well-limed  land  are  more  feeding  for  both  cattle  and  sheep. 
And  the  hill  pastures  on  limestone  soils,  like  those  of  Derby- 
ehire,  continue  longer  green  in  autumn,  and  yield  a  greater  year- 
ly return  of  milk  and  cheese,  than  the  soils  which  are  produced 
from  sandstone  rocks. 


CROPS   AND   BAINS    CARRY   AWAY    LIME.  259 

Bat  this  superiority  gradually  diminishes  year  by  year,  in  land 
artificially  limed,  till  it  returns  again  nearly  to  its  original  con- 
dition. On  analysing  the  soil  when  it  has  reached  this  state,  the 
lime  which  had  been  added  is  found  to  be  in  a  great  measure 
gpne.  In  this  condition  the  land  must  either  be  limed  again, 
or  must  be  left  to  produce  sickly  and  unremunerating  crops. 

This  removal  of  the  lime  arises  from  several  causes. 

1.  TJiA  lime  naturally  sinks, — ^more  slowly  perhaps  in  arable 
than  in  pasture  or  meadow  land,  because  the  plough  is  continu- 
ally bringing  it  to  the  surface  again.  But  even  in  arable  land, 
it  gets  at  last  beyond  the  reach  of  the  plough,  so  that  either  a 
new  dose  must  be  added  to  the  upper  soil,  or  a  deeper  plough- 
ing must  bring  it  again  to  the  surface. 

2.  The  crops  carry  away  a  portion  of  lime  from  the  soil. — Thus 
the  following  crops,  including  grain  and  straw,  or  tops  and 
bulbs,  carry  off  respectively — 


Of  lime 

25  bushels,  wheat,  about 

13  lb. 

40     ....        barley, 

17  " 

50     ....        oats, 

22  " 

20  tons  of  turnips,  about 

118  " 

8    ...        potatoes, 

40  " 

2    ...        red  clover, 

11  " 

2    ...        rye  grass, 

30  " 

The  above  quantities  are  not  constant,  and  much  of  the  lime 
is  no  doubt  returned  to  the  land  in  the  straw,  the  tops,  and  the 
manure  ;  yet  still  the  land  cannot  fail  to  suffer  a  certain  annual 
loss  of  lime  from  this  cause. 

3.  The  rains  wash  out  lime  from  the  land. — ^The  rain-water 
that  descends  upon  the  land  holds  in  solution  carbonic  acid 
which  it  has  absorbed  from  the  air.  But  water  charged  with 
carbonic  acid  is  capable  of  dissolving  carbonate  of  lime  ;  and 
thus  year  after  year  the  rains,  as  they  sink  to  the  drains,  or 
run  over  the  surface,  slowly  remove  a  portion  of  the  lime  which 
the  soil  contains.  Acid  substances  are  also  formed  naturally  by 
the  decay  of  vegetable  matter  in  the  land,  by  which  another 


260  CHEMICAL  EFFECTS   OF  LIME  UPON  THE   SOIL. 

portion  of  the  lime  is  rendered  easily  soluble  in  water,  and 
therefore  readily  removable  by  every  shower  that  falls.  It  is  a 
necessary  consequence  of  this  action  of  the  rains,  that  lime 
must  be  added  more  frequently,  or  in  larger  doses,where  much 
rain  falls  than  where  the  climate  is  comparatively  dry. 

SECTION    VII. CIRCUMSTANCES    WHICH    MODIFY    THE    EFFECTS    OP 

LIME   UPON   THE    SOIL, 

There  are  four  circumstances  of  great  practical  importance 
in  regard  to  the  action  of  lime,  which  cannot  be  too  carefully 
borne  in  mind.    These  are — 

1,  That  lime  has  little  or  no  marked  effect  upon  soils  in  which 
organic — that  is  animal  or  vegetable — matter  is  greatly  de- 
ficient, 

2,  That  its  apparent  effect  is  inconsiderable  during  the  first 
year  after  its  application,  compared  with  that  which  it  produces 
in  the  second  and  third  years, 

3,  That  its  effect  is  most  sensible  when  it  is  kept  near  the 
surface  of  the  soil,  and  gradually  becomes  less  as  it  sinks 
towards  the  subsoil.     And, 

4,  That  under  the  influence  of  lime  the  organic  matter  of  the 
soil  disappears  more  rapidly  than  it  otherwise  would  do,  and 
that,  as  this  organic  matter  becomes  less  in  quantity,  fresh  ad- 
ditions of  lime  produce  a  less  sensible  effect, 

SECTION    VIII. CHEMICAL     EFFECTS    OF    CAUSTIC     LIME     UPON  THE 

SOIL, 

The  chemical  effects  of  lime  upon  the  soil  in  the  caustic  and 
mild  states  are  chiefly  the  following  : — 

a.  When  laid  upon  the  land  in  the  caustic  state,  the  first  ac- 
tion of  lime  is  to  combine  immediately  with  every  portion  of  free 
acid  matter  it  may  contain,  and  thus  to  sweeten  the  soil 
Some  of  the  compounds  it  thus  forms  being  soluble  in  water, 
enter  into  the  roots  and  feed  the  plant,  or  are  washed  out  by 


CHEMICAL   EFFECTS    OF   CAUSTIC    LIME.  261 

the  springs  and  rains  ;  while  other  compounds  which  are  insol- 
uble remain  more  permanently  in  the  soil. 

b.  Another  portion  decomposes  certain  saline  compounds 
of  iron,  manganese,  and  alumina  which  naturally  form  them- 
selves in  the  soil,  and  thus  renders  them  unhurtful  to  vegetation. 
A  similar  action  is  exerted  upon  some  of  the  compounds  of 
potash,  soda,  and  ammonia — if  any  such  are  present — by  which 
these  substances  are  set  at  liberty,  and  placed  within  the  reach 
of  the  plant. 

c.  Its  presence  in  the  caustic  state  further  disposes  the  organ- 
ic matter  of  the  soil  to  undergo  more  rapid  decomposition — it 
being  observed  that,  where  Ume  is  present  in  readiness  to  com- 
bine with  the  substances  produced  during  the  decay  of  organic 
matter,  this  decay,  if  other  circumstances  be  favourable,  will 
proceed  with  much  greater  rapidity.  The  reader  will  not  fail  to 
recollect  that,  during  the  decomposition  of  organic  substances 
in  the  soil,  many  compounds  are  formed  which  are  of  importance 
in  promoting  vegetation. 

d.  It  is  known  that  a  portion  at  least  of  the  nitrogen  which 
naturally  exists  in  the  decaying  vegetable  matter  of  the  soil  is 
in  a  state  in  which  it  is  very  sparingly  soluble,  and  therefore 
becomes  directly  available  to  plants  with  extreme  slowness. 
But  when  heated  with  slaked  lime  in  our  laboratories,  such 
compounds  readily  give  off  their  nitrogen  in  the  form  of  ammo- 
nia. It  is  not  unlikely,  therefore,  that  hot  lime  produces  a 
similar  change  in  the  soil,  though  more  slowly — hastening,  as 
above  stated,  the  general  decomposition  of  the  whole  organic 
matter,  but  specially  separating  the  nitrogen,  and  causing  or  en- 
abling it  to  assume  the  form,  first  of  ammonia,  and  afterwards 
of  nitric  acid,  both  of  which  compounds  the  roots  of  plants  can 
readily  absorb. 

c.  Further,  quick-lime  has  the  advantage  of  being  soluble  to  a 
considerable  extent  in  cold  water,  forming  lime-water.  Thus 
the  complete  diffusion  of  lime  through  the  soil  is  aided  by  the 
power  of  water  to  carry  it  in  solution  in  every  direction. 


863  CHEHICAL   EFFECTS   OF  UILD  LIUS. 


SECTION   IX. CHEMICAL  EFFECTS    OF   MILD   LIME   WHEN  APPLIED   10 

THF   SOIL. 

When  it  has  absorbed  carbonic  acid,  and  become  reconverted 
into  carbonnte,  the  original  caustic  lime  has  no  chemical  virtue 
over  chalk  or  crushed  limestone,  rich  shell-sand,  or  marl.  It 
has,  however,  the  important  mechanical  advantage  of  being  in 
the  form  of  a  far  finer  powder  than  any  to  which  we  can  reduce 
the  limestone  by  art — in  consequence  of  which  it  can  be  more 
uniformly  diffused  through  the  soil,  and  placed  within  the  reach 
of  every  root,  and  of  almost  every  particle  of  vegetable  matter 
that  is  undergoing  decay.  I  shall  mention  only  three  of  the 
important  purposes  which,  in  this  state  of  carbonate,  lime  serves 
upon  the  land. 

a.  It  directly  affords  food  to  the  plant,  which,  as  we  have 
seen,  languishes  where  lime  is  not  attainable.  It  serves  also  to 
convey  other  food  to  the  roots  in  a  state  in  which  it  can  be 
made  available  to  vegetable  growth.* 

b.  It  neutralises  (removes  the  sourness^  of  all  acid  substances 
as  they  are  formed  in  the  soil,  and  thus  keeps  the  land  in  a 
condition  to  nourish  the  tenderest  plants.  This  is  one  of  the 
important  agencies  of  'shell-sand,  when  laid  on  undrained  grass 
or  boggy  lands  ;  and  this  effect  it  produces  in  common  with 
wood  ashes  and  many  similar  substances. 

c.  During  the  decay  of  organic  matter  in  the  soil,  it  aids  and 
promotes  the  slow  natural  production  of  nitric  acid.  With  this 
acid  it  combines  and  forms  nitrate  of  lime — a  substance  very  sol- 
uble in  water — entering  readily,  therefore,  into  the  roots  of 
plants,  and  producing  effects  upon  their  growth  which  are  very 
similar  to  those  of  the  now  well-known  mVrafc  of  soda.  The  success 
of  frequent  ploughings,  harrowings,  hoeings  and  other  modes  of 
stirring  the  land,  is  partly  owing  to  the  facilities  which  these 
operations  afford  for  the  production  of  this  and  other  natural 
nitrates 


OVER-LIMED   SOILS. 


263 


SECTION  X. — WHAT  IS  MEANT  BY  OVER-LIMING  ? — PROPORTION  OF 
LIME  IN  OVER-LIMED  LAND. HOW  OVER-LIMING  IS  TO  BE  REM- 
EDIED. 

It  is  known  that  the  frequent  addition  of  lime,  even  to  com- 
paratively stifiF  soils  long  kept  in  arable  culture,  will  at  length 
so  open  them  that  the  wheat  crop  becomes  uncertain,  and  is 
especially  liable  to  be  thrown  out  in  winter. 

To  lighter  soils,  again,  and  especially  to  such  as  are  reclaim- 
ed from  a  state  of  heath,  and  contain  much  vegetable  matter, 
the  addition  of  a  large  dose  of  lime  opens  and  loosens  them, 
often  to  such  a  degree  that  they  sound  hollow,  and  sink  under 
the  foot.  This  effect  is  usually  ascribed  to  an  over-dose  of  lime, 
and  the  land  is  commonly  said  to  be  over-limed.  In  this  state  it 
refuses  to  grow  oats  and  clover,  though  turnips  and  barley 
thrive  well  upon  it. 

Being  desirous  of  ascertaining  the  proportion  of  lime  re- 
ally present  in  land  which  has  been  brought  by  lime  into  such  a 
condition,  I  obtained  from  Sir  George  Macpherson  Grant  a 
number  of  soils  from  different  fields  upon  his  estate  of  Ballin- 
dalloch,  and  caused  them  to  be  analysed  in  my  laboratory.  The 
results  of  the  analyses  were  as  follows  : — 


n 

•ITS 

Sutherland 
Park- 
soil  and 
subsoil. 

Organic  matter, 

10.29 

9.54 

5.65 

5.73 

5.2.^ 

Salts  soluble  ia  water, 

0.45 

0.15 

0.50 

0.15 

0.44 

Oxide  of  iron, 

2.49 

3.68 

0.50 

0.96 

2.04 

Alumina, 

1.71 

2.54 

1.11 

1.48 

1.15 

Carbonate  of  lime,    . 

1.40 

0.69 

1.10 

0.98 

0.67 

Oxide  of  manganese, 

trace. 

0.72 

trace. 

trace. 

0.22 

Carbonate  of  magnesia, 

do. 

trace. 

do. 

do. 

trace. 

Insoluble  matter,  chiefly  sand,  . 

81.77 

82.79 

91.20 

90..34 

89.60 

98.11 

100.11 

100.06 

99.64 

99.35  ' 

264  HOW  TO  TREAT  SUCH   SOILS. 

In  all  these  soils  the  quantity  of  carbonate  of  lime  was 
much  less  than  is  usually  found  in  fertile  soils.  I  inferred, 
therefore,  that  the  effects  ascribed  to  the  lime  were  not  due  to 
its  presence  in  too  large  a  proportion,  compared  with  other 
soils. 

Two  other  facts  aided  me  in  arriving  at  a  correct  conclusion 
upon  the  subject. 

1.  That  these  same  soils  were  known  to  produce  good  oats 
when  they  had  been  some  years  in  pasture,  or  when  turnips 
had  been  eaten  off  them  with  sheep,  and  the  ground  thus 
trodden  and  consolidated  by  their  feet. 

2.  That  oats  and  clover  prefer  a  stiffer,  stronger  soil  iu 
which  to  fix  their  roots,  while  turnips  and  barley  delight  in  a 
light  and  open  soil. 

It  was  therefore  the  mechanical,  and  not  the  chemical  con- 
dition of  the  soils,  which  caused  the  failure  of  the  turnip  and 
clover  crops.  Consolidate  them  by  any  means,  and  these 
crops  would  become  more  certain.  The  remedies,  therefore, 
were — 

a.  To  eat  off  the  turnips  always  with  sheep  ; — or 

h.  To  consolidate  the  loose  and  open  soil  by  the  use  of  a 
heavy  roller,  a  clod-crusher  or  peg-roller,  or  other  similar  me- 
chanical means; — or 

c.  To  use  the  cultivator  as  much  as  possible  instead  of  the 
plough,  and  thus  to  avoid  the  artificial  loosening  of  the  soil 
which  is  caused  by  frequent  ploughing. 

Still  the  questions  were  unsolved, — In  what  way  does  the 
lime  produce,  or  aid  the  plough  in  producing,  this  opening  of 
the  soil  ? — and  how  are  these  effects  to  be  prevented  in  fu- 
ture ? 

I  offer  the  following  considerations,  as  affording  a  conjectu- 
ral explanation  of  this  matter  : — 

1.  The  lime,  in  whatever  state  it  is  added  to  the  land,  as- 
sumes in  a  short  time  the  state  of  carbonate. 

2.  In  soils  which  are  rich  in  decaying  vegetables  much  acid 


EXHAUSTING   EFFECTS   OF   LIME.  265 

matter  is  gradually  produced  by  the  action  of  the  air.  The 
acids  thus  produced  decompose  the  carbonate  of  lime,  and  libe- 
rate its  carbonic  acid  more  or  less  copiously. 

3.  The  effect  of  this  liberation  of  the  carbonic  acid  gas  may 
be  to  heave  up  the  land,  to  loosen  it  and  lighten  it  under  the 
foot.  In  heavy  lands  this  may  be  less  perceived,  both  because 
they  are  naturally  denser  and  more  difficult  to  heave  up,  and 
because  they  contain  less  vegetable  matter,  and  consequently 
produce  less  of  these  acid  substances  in  the  soil.  In  light 
peaty  or  thin  moorish  soils,  however,  which  are  rich  in  decay- 
ing plants,  the  particles  of  soil  are  more  readily  lifted  up  and 
separated  from  one  another. 

"Will  this  supposed  action  never  cease  ?  It  is  doubtful  if  it 
will,  until  the  nature  of  the  soil  is  altered — by  the  gradual  re- 
moval of  the  lime — by  a  diminution  of  the  quantity,  and  a 
change  in  the  nature  of  the  decaying  vegetable  matter — or  by 
a  ^permanent  solidifying  of  the  land. 

This  last  change  may  be  effected  either  by  a  top-dressing  of  clay, 
sand,  limestone-gravel,  or  other  heavy  matter,  or  by  bringing  up 
a  heavier  subsoil  from  below.  Where  the  temporary  solidifica- 
tion produced  by  eating  off  with  sheep  and  the  use  of  a  roller  is 
not  approved  of,  the  improvement  of  over-limed  land  is  to  be 
sought  for  in  draining,  subsoiling  so  as  to  admit  the  air  into  the 
under-soil,  and,  after  a  time,  in  bringing  up  and  mixing  with  the 
surface  a  sufficient  portion  of  this  under-soil. 

SECTION  XI. — EXHAUSTIXG  EFFECTS  OF  LIME. — IS  LIME   NECESSARILY 
EXHAUSTING  ? 

The  exhausting  effects  of  lime  have  been  remarked  from  the 
earliest  times.  It  causes  larger  crops  to  grow  for  a  certain 
number  of  years,  after  which  the  produce  diminishes,  till  at  length 
it  becomes  less  than  before  lime  was  applied  to  it.  Hence  the 
origin  of  the  proverb  that  "  Lime  enriches  the  fathers  and  im- 
poverishes the  sons." 
1^ 


266  ORGANIC   HATTER  DIMINISHES    IN   THE   SOIL. 

Two  interesting  questions,  therefore,  suggest  themselves  in 
connection  with  this  circumstance.  How  is  this  exhaustion  pro- 
duced ?  Is  it  a  necessary  consequence  of  the  addition  of  lime, 
or  can  it  be  prevented  ? 

It  has  already  been  stated  that  lime  promotes  those  chemical 
changes  of  the  organic  part  of  the  soil  by  which  it  is  rendered 
more  serviceable  to  the  growth  of  plants.  But  in  consequence 
of  this  action,  the  proportion  of  organic  matter  in  the  soil  grad- 
ually diminishes  imder  the  prolonged  action  of  lime,  and  thus 
the  soil  becomes  less  rich  in  those  substances  of  organic  origin 
on  which  its  fertility  in  some  degree  depends. 

Again,  lime  acts  also  on  the  mineral  matter  of  the  soil,  and 
prepares  it  for  more  abundantly  feeding  the  plant. 

Now,  as  the  crops  we  reap  carry  off  not  only  organic  but  min- 
eral matter  also  from  the  soil,  anything  which  prepares  that 
mineral  matter  more  abundantly  for  the  use  of  the  plant  must 
cause  also  a  more  rapid  diminution  of  those  mineral  substances 
on  which,  as  well  as  upon  its  organic  matter,  the  fruitfulness  of 
the  soil  is  dependent. 

By  this  mode  of  action,  therefore,  arises  the  exhaustion  which 
universal  experience  has  ascribed  to  the  use  of  lime. 

But  without  reference  to  the  chemical  processes  by  which  it 
is  brought  about,  a  common-sense  view  of  the  question  sulBcient- 
ly  explains  how  the  exhaustion  arises. 

It  is  conceded  that  the  crops  we  grow  rob  the  soil  both  of 
m'ganic  and  inorganic  matter.  A  double  crop  will  take  twice 
as  much,  a  triple  crop  three  times  as  much,  and  so  on.  And  the 
more  we  take  out  in  one  year,  the  more  rapidly  will  the  land  be 
exhausted.  Now,  if  lime,  by  its  mode  of  action,  enables  us  in 
the  same  time  to  extract  three  or  four  times  as  much  matter 
from  the  soil  in  the  form  of  increased  crops,  it  must  so  much 
the  more  rapidly  exhaust  the  soil,  in  the  same  way  as  wo 
should  drain  a  well  sooner  by  taking  out  fifty  than  by  remov- 
ing only  five  gallons  a-day. 

But  we  can  restore  to  the  soil  what  crops  carry  off.    By 


THE   SOIL  CAN   BE  RESTORED   BY   MANURE,    &C,  267 

farmyard  manure,  and  by  saline  applications,  we  can  return 
everything  which  the  lime  enables  us  thus  to  extract,  and  we 
can  thus  preserve  its  fertility  unimpaired.  Manure,  therefore, 
in  proportion  to  the  crops  taken  off,  and  lime,  will  cease  to  be 
exhausting.    There  is  much  wisdom  in  the  rhyme, 

"Lime  and  lime  without  manure 
Will  make  both  land  and  farmer  poor." 


CHAPTER    XX. 

Impiwvement  of  the  soil  by  paring  and  burning. — Use  and  properties  of 
burned  earth  and  burned  clay  as  improvers. — Efifects  of  burning  upon 
clay. — Smother-burning  and  over-burning. — How  they  improve  the  soil. 
— Improvement  by  means  of  irrigation. — Irrigation  a  kind  of  manuring.— 
How  waters  manure  the  land. — Composition  of  the  water  of  the  Hamp- 
stead  water-works. — Different  virtues  of  natural  streams. 

There  remain  still  a  few  important  modes  of  improving  the 
soil  by  forms  of  mineral  and  organic  manuring,  which  it  is  ne- 
cessary briefly  to  notice, 

SECTION   I. IMPROVEMENT   OF   THE    SOIL  BY  PARING   AND  BURNING. 

A  mode  of  improvement  often  resorted  to  on  poor  lands 
is  the  paring  and  burning  of  the  surface.  The  effect  of  this 
treatment  is  easily  understood.  The  matted  sods  consist  of 
a  mixture  of  much  vegetable  with  a  comparatively  small 
quantity  of  earthy  matter.  When  these  are  burned,  the  ash 
only  of  the  plants  is  left,  intimately  mixed  with  the  calcined 
earth.  To  strew  this  mixture  over  the  soil  is  much  the  same  as 
to  dress  it  with  peat  or  wood  ashes,  the  beneficial  effects  of 
which  are  almost  universally  recognised.  And  the  beneficial 
influence  of  the  ash  itself  is  chiefly  due  to  the  ready  supply  of 
inorganic  food  it  yields  to  the  seed,  and  to  the  effect  which  the 
potash  and  soda,  &c.,  which  it  contains  exercise  either  in  prepar- 
ing organic  food  in  the  soil,  or  in  assisting  its  assimilation  in  the 
interior  of  the  plant. 

Another  part  of  this  process  is,  that  the  roots  of  the  weeds 
and  poorer  grasses  are  materially  injured  by  the  paring,  and 
that  the  subsequent  dressing  of  ashes  is  unfavorable  to  their 
further  growth. 


BURNED  EARTH  AND  CLAY.  26S 

It  is  besides  alleged,  and  I  believe  with  truth,  that  poor  old 
grass  land,  when  plonghed  up,  is  sometimes  so  full  of  insects 
that  the  success  of  any  corn  or  green  crop  put  into  it  becomes 
very  doubtful.  When  pared,  these  insects  collect  in  the  sod, 
and  are  destroyed  by  the  subsequent  burning. 

Paring  and  burning  is  a  quick  method  of  bringing  land  into 
tillage^  and  will  secure  one  or  two  good  crops.  But  it  is 
exhausting,  and  the  prudent  man  will  rarely  have  recourse 
to  it  for  the  purpose  of  reclaiming  land  which  is  to  be  kept  in 
constant  tillage.  It  is  very  much  less  practised  now  than  it 
was  twenty  or  thirty  years  ago. 

Another  evil  also  follows  the  practice  of  paring  and  burning. 
Where  the  land  has  little  fall  for  drainage — ^is  raised,  that  is, 
only  a  few  feet  above  the  level  of  the  nearest  brook — ^this 
paring  and  burning  gradually  lowers  the  level,  and  makes  it 
impossible  at  last  to  drain  it.  In  JSTorthamptonshire  I  have 
been  told  of  pieces  of  land,  a  few  years  ago  two  feet  above 
the  water  level,  which  are  now  brought  down  to  that  level  by 
the  repetition  of  this  hurtful  practice.  This  is  certainly  enriching 
the  farmers  and  impoverishing  the  sons. 

SECTION    II. — ON     THE     USE     AND   PROPERTIES     OF    BURNED   EARTH 
AND   CLAY  AS    IMPROVERS, 

1°.  Burned  earth  and  clay  have  long  been  recognised  by  the 
farmer  as  useful  applications,  in  certain  circumstances,  to  his 
land.  Mixed  with  much  vegetable  matter  of  any  kind,  and 
burned  slowly  and  without  free  access  of  air,  stiff  soils  of  all 
sorts  will  give  blackened  heaps,  which  may  be  spread  with  ad- 
vantage as  a  top-dressing,  or  employed,  as  in  China,  to  cover  the 
seed  after  it  has  been  committed  to  the  earth. 

To  the  light  porosity  of  the  earth,  and  to  the  action  of  the 
vegetable  ashes  which  are  mixed  with  it,  the  beneficial  influence 
of  such  burned  mixtures  is  distinctly  to  be  ascribed. 

2°.  Burned  day,  in  which  little  organic  matter  exists,  and 


270  CAUSE   OF  THEIR  USEFUL  ACTION. 

with  which  little  is  mixed  during  the  burning,  must  owe  any 
fertilising  properties  it  possesses  to  a  different  cause.  Such 
clay,  properly  prepared,  has  in  numerous  instances  been  found 
beneficial  when  applied  to  the  land.  It  is  usually  laid  on  in 
large  doses,  and  acts  both  mechanically  and  chemically. 

a.  Mechanically,  in  rendering  the  soil  more  friable,  so  that  it 
can  be  worked  with  less  labor,  and  in  especially  aiding  the  cul- 
ture of  green  crops. 

h.  Chemically,  in  considerably  increasing  the  produce.  Thus 
Mr.  Pusey  found  a  dressing  of  burned  Oxford  clay  to  increase 
his  wheat  crop  from  31 1  to  45 1  bushels  per  imperial  acre. 
And  Mr.  Danger,  who  farms  on  the  new  red  sandstone,  near 
Bridgewater,  says,  that  a  soil  which  he  found  "  quite  sterile, 
has,  by  the  application  of  burned  clay,  become  totally 
changed."* 

It  is  equally  true,  however,  that  burned  clay  has  often  failed 
to  do  any  good — that  the  practice  of  burning  clay,  which  is 
common  in  some  districts,  is  for  this  reason  never  adopted  in 
others — and  that  clay  from  the  same  locality  may  or  may  not 
do  good  according  to  the  method  of  burning. 

All  this  is  easily  explained  when  the  true  cause  of  the 
chemical  action  of  burned  clay  is  understood. 

3°.  Cause  of  its  useful  chemical  action. — All  clays  contain 
sensible  quantities  of  most  of  the  mineral  substances — ^potash, 
soda,  lime,  magnesia,  phosphoric  acid,  &c. — which  plants  re- 
quire for  their  healthy  growth.  They  are,  however,  in  a  com- 
paratively insoluble  condition,  which  circumstance,  united  to 
the  stiffness  of  the  clay,  prevents  the  roots  of  plants  from 
readily  taking  them  up.  When  the  clays  are  burned  by  a  gen- 
tle heat,  however,  the  chemical  condition  of  the  constituents  of 
the  clay  is  altered,  and  the  substances  which  plants  require  are 
rendered  more  soluble.  After  the  burning,  both  water  and 
acids  will  dissolve  out  more  from  the  same  weight  of  dry  clay, 

*  SoycU  Agricuitural  Journal,  vl  417,  and  xii.  509. 


OVER-BUBNED   CLAY,  211 

ancf  the  matter  thus  dissolved  contains  a  large  proportion  of 
those  mineral  ingredients  which  all  plants  contain.  In  one  ex- 
periment, I  found  that  a  ton  of  clay  which,  in  the  natural 
state,  gave  to  water  only  11  lb.  of  mineral  matter,  yielded 
readily  36  lb.  after  being  burned.  Besides,  the  clay  is  rendered 
more  porous  by  the  burning,  so  that  water  and  the  roots  of 
plants  can  penetrate  more  easily  to  take  up  the  soluble  matter. 

Again,  of  burned  clay,  50  to  100  tons  an  acre  is  not  an  un- 
usual application.  Now,  at  36  lb.  to  the  ton,  the  largest  dose 
would  yield  to  water  not  less  than  3600*  lb.  of  soluble  mine- 
ral matter  ;  while  the  whole  quantity  of  such  matter  carried  off 
in  a  four  years'  rotation,  from  our  best  farms,  (p.  69,)  is  only 
1300  lb.  It  is  not  surprising,  therefore,  knowing,  as  we  do, 
how  applications  of  saline  matter  increase  the  crops,  that  so 
great  and  ready  a  supply  of  such  matter  in  the  burned  clay 
should  produce  a  marked  effect  upon  the  fertility  of  the  laud 
upon  which  it  is  spread. 

But,  further,  all  clays  have  not  the  same  composition.  Some 
contain  more  lime,  others  more  magnesia,  others  more  potash  or 
soda,  and  others  more  phosphoric  acid  ;  while  some,  again,  con- 
tain so  little  of  any  of  these  substances  as  to  produce  no  sensible 
effect  when  burned  and  laid  upon  the  land.  Thus  the  chemical 
composition  of  a  clay  determines  whether  or  not  it  can  be  burned 
and  applied  to  advantage. 

Those  clays  are  likely  to  suit  well  which  contain  most  alkaline 
matter,  (potash  and  soda  ;)  next  those  which  contain  a  consid- 
erable percentage  of  lime  or  magnesia,  or  phosphoric  acid  ;  and, 
best  of  all,  those  which  with  the  alkaline  contain  also  the  cal- 
careous matter.  Hence  it  is  that  to  clays  which  contain  little 
lime  it  is  a  judicious  recommendation  that  a  quantity  of  slaked 
lime  should  be  sprinkled  upon  the  clay  during  its  preparation  for 
burning. 

In  the  fourth  place,  it  is  remarkable  that,  by  too  complete 
a»d  prolonged  a  burning,  the  clay  is  again  rendered  less  sola- 

*  Mx^erimental  AgricuUure,  p.  261. 


212  lilPROVEMENT   OF 

ble  in  water  and  in  acids  than  before.  Hence  the  evil  of  ove? 
burning,  as  it  is  called,  and  the  reason  why  the  same  clay  pre- 
pared in  different  ways  does  not  produce  the  same  good  effects. 
The  method  of  slow  smother-hnrning — the  heat  being  kept  low, 
and  free  access  of  air  prevented — is  that  which  gives  the  most 
constant  good  results. 

Lastly,  I  notice,  as  a  beneficial  consequence  of  burning,  that 
the  burned  clay,  being  generally  porous,  absorbs  ammoniacal 
and  other  vapors  from  the  air  and  from  the  soil  more  readily 
and  abundantly  than  before,  and  fixes  them  for  the  use  of  plants. 
In  the  black  smother-burned  clay,  which  contains  much  iron, 
this  metal,  in  absorbing  oxygen  from  the  air,  may  even  give 
rise  to  the  formation  of  ammonia,  and  thus,  in  another  chemical 
manner,  act  favorably  upon  the  soil. 

Advantage  is  taken  of  this  porous  quality  of  burned  clay  by 
some  English  farmers — as  by  Mr.  Randall,  of  Chadbury,  near 
Evesham — to  absorb  and  preserve  the  droppings  of  sheep. 
Under  house-fed  sheep,  kept  upon  boards  or  otherwise,  a  la^er 
of  burned  clay  is  spread,  upon  which  the  droppings  fall  :  from 
time  to  time  fresh  layers  are  added  to  the  surface,  till  it  be- 
comes necessary  to  remove  the  whole.  In  this  way,  the  smell 
of  the  dung  never  becomes  excessive,  and  the  clay  is  rendered  so 
rich  that  10  tons  of  it  are  found  equal,  in  the  raising  of  turnips, 
to  4  cwt.  of  guano. 

SECTION   III. ON  THE  IMPROVEMENT   OF  THE   LAND   BY   IRRIGATION. 

The  irrigation  of  the  land  is,  in  general,  only  a  more  refined 
method  of  manuring  it.  The  nature  of  the  process  itself,  how- 
ever, is  different  in  different  countries,  as  are  also  the  kind  and 
degree  of  effect  it  produces,  and  the  theory  by  which  these 
effects  are  to  be  explained. 

1.  In  dry  and  arid  climates,  where  rain  rarely  falls,  the  soil 
may  contain  all  the  elements  of  fertility,  and  require  only  water 
to  call  them  into  operation.    In  such  cases — as  in  the  irriga> 


THE   LAND    BY    IKEIGATION.  2t3 

tions  practised  so  extensively  in  Eastern  countries,  and  without 
which  whole  provinces  in  Africa  and  Southern  America  would 
lie  waste — it  is  unnecessary  to  suppose  any  other  virtue  in 
irrigation  than  the  mere  supply  of  water  it  affords  to  the  parch- 
ed and  cracking  soil. 

But  in  cUmates  such  as  our  own,  there  are  several  other  be- 
neficial purposes  in  reference  to  the  soil,  which  irrigation  may, 
and  some  of  which,  at  least,  it  always  does  serve — thus, 

2.  The  occasional  flow  of  piore  water  over  the  surface,  as  in 
our  irrigated  meadows,  and  its  descent  into  the  drains,  where 
the  drainage  is  perfect,  washes  out  acid  and  other  noxious  sub- 
stances naturally  generated  in  the  soil,  and  thus  purifies  and 
sweetens  it.  The  beneficial  effect  of  such  washing  will  be  rea- 
dily understood  in  the  case  of  peat-lands  laid  down  to  water- 
meadow,  since,  as  every  one  knows,  peaty  soils  abound  in 
matters  unfavorable  to  general  vegetation.  These  substances 
are  usually  in  part  drawn  off  by  drainage,  and  in  part  destroy- 
ed by  lime  and  by  exposure  to  the  air,  before  boggy  lands  can 
be  brought  into  profitable  cultivation. 

3.  But  it  seldom  happens  that  perfectly  jjwre  water  is  employ- 
ed for  the  purposes  of  irrigation.  The  waters  of  rivers,  as  they 
are  diverted  from  their  course  for  this  purpose,  are  more  or  less 
loaded  with  mud  and  other  fine  particles  of  matter,  which  are 
either  gradually  filtered  from  them  as  they  pass  over  and  through 
the  soil,  or,  in  the  case  of  floods,  subside  naturally  when  the 
waters  come  to  rest.  Or,  in  less  frequent  cases,  the  drainings  of 
towns  and  the  water  from  common  sewers,  or  from  the  little 
streams  enriched  by  them,  are  turned  with  benefit  upon  the  fa- 
voured fields.  These  are  evidently  cases  of  gradual  and  uniform 
manuring. 

4.  Even  where  the  water  employed  is  clear  and  apparently 
undisturbed  by  mud,  it  almost  always  contains  ammonia,  nitric 
acid,  and  other  organic  and  saline  substances  grateful  to  the 
plant  in  its  search  for  food,  and  which  plants  always  contrive  to 
extract,  more  or  less  copiously,  as  the  water  passes  over  their 

12* 


2Y4 


COMPOSITION    OF  THE  HAMPSTEAD   WATER. 


leaves  or  along  their  roots.  The  purest  spring  waters  and 
mountain  streams  are  never  entirely  free  from  impregnations  of 
mineral  and  vegetable  or  animal  matter.  Every  fresh  access 
of  water,  thsrefore,  affords  the  grass  in  reality  another*  liquid 
manuring. 

5.  In  illustration  of  this,  I  insert  the  following  analyses  of  the 
water  supplied  by  the  Hampstead  Water-works,  for  the  use  of 
the  city  of  London,  as  given  by  Mr.  Mitchell.  It  contains  in  all 
40  grains  of  dry  matter  to  the  imperial  gallon,  which  consists 
of— 


Carbonate  of  lime,           .             .             . 

3,83  grains. 

Carbonate  of  magnesia^  . 

3.41      ... 

Phosphate  of  lime,          .              , 

0.28      ... 

Sulphate  of  lime,            .              .              , 

4.42       ... 

Sulphate  of  potash, 

3.28       .> 

Sulphate  of  soda, 

4.81       ... 

Chloride  of  sodium  (common  salt,) 

17.76       ... 

Silica  (soluble,)               .              , 

0.28       ... 

Crenic  acid,                     .              .              .              . 

0.17       ... 

Aprocrenic  acid,             .              ,             ,              , 

0.08       ... 

Other  organic  matters,  .              .              .              . 

1.72       ... 

Oxides  of  iron  and  manganese, 

traces 

40.04 


In  this  list  of  substances,  we  recognise  nearly  every  mineral 
ingredient  which  is  found  in  the  ash  of  plants.  But,  in  addition 
to  these  ingredients,  nearly  all  river  and  spring  waters  contain 
appreciable  quantities  of  ammonia  and  of  nitric  acid,  which  are 
not  mentioned,  and  were  probably  not  sought  for  by  Mr.  Mitchell. 
It  is  not  surprising,  therefore,  that  waters  containing  such  sub- 
stances, in  an  available  form,  should  promote  vegetation  when 
used  for  the  purpose  of  irrigation. 

6.  The  kind  of  saline  substances  which  spring  water  or  that 
of  brooks  contains,  depends  upon  the  nature  of  the  rocks  or  soils 
from  which  it  issues  or  over  which  it  runs.  In  countries  Avhere 
granite  or  mica-slate  abounds,  potash  and  soda,  and  even  mag- 
nesia, may  be  expected  in  notable  quantities,  while  in  limestone 
districts  the  water?  <ire  generally  charged  with  lime.     When 


WATERS   DIFFER   IN    NATURAL   VIRTUE.  215 

spread  over  the  fields,  these  latter  waters  supply  Ume  to  the 
growing  plants,  and  so  affect  the  general  fertility  of  the  soil  as 
to  render  almost  unnecessary  the  direct  application  of  lime 
to  the  land.  The  value  of  the  mountain  streams  for  the  purpose 
of  irrigation  in  limestone  districts  is  so  well  known,  that  some 
have  been  inclined  to  undervalue  all  the  constituents  of  natural 
waters,  and  to  ascribe  little  worth  as  irrigators  to  the  clear 
waters  of  brooks  and  springs  which  are  not  rich  in  lime.  This 
opinion,  however,  is  not  in  accordance  with  the  results  of  the  an- 
alyses made  in  my  laboratory,  of  waters  which  have  been  pro- 
fitably employed  for  irrigation. 

1.  Flowing  water  also  diinks  in  from  the  air,  as  it  passes 
along,  a  portion  of  the  oxygen  and  carbonic  acid  of  which  the 
atmosphere  in  part  consists.  These  gaseous  substances  it 
brings  in  contact  with  the  leaves  at  every  moment,  or  it  carries 
them  down  to  the  roots  in  a  form  in  which  they  can  be  readily 
absorbed  by  the  parts  of  the  plant.  It  is  not  unlikely  that,  in 
consequence  of  this  mode  of  action,  even  absolutely  pure  water 
would  act  beneficially  if  employed  in  irrigating  the  soil. 

8.  Further,  the  constant  presence  of  water  keeps  all  the 
parts  of  the  plant  in  a  moist  state,  allows  the  pores  of  the 
leaves  and  stems  to  remain  open,  retards  the  formation  of  hard 
woody  fibre,  and  thus  enables  the  growing  vegetable,  in  the 
same  space  of  time,  to  extract  a  larger  supply  of  food,  espe- 
cially from  the  air.  In  other  words,  it  promotes  and  enlarges 
its  growth. 

In  the  refreshment  continually  afibrded  to  the  plant  by  a 
plentiful  supply  of  water — in  the  removal  of  noxious  substances 
from  the  soil — in  the  frequent  additions  of  enriching  food, 
saline,  organic,  or  gaseous'  to  the  land — in  the  soft  and  porous 
state  in  which  it  retains  the  parts  of  the  plant,  the  efficiency 
of  irrigation  seems  almost  entirely  to  consist. 

9.  To  one  other  interesting  point  I  must  advert.  It  is 
known  that  waters  whi  ?h  have  passed  over  the  surface  of  a 
field  become  sensibly  less  fertilising.     This  is  easily  explained. 


276  SPRING    WATERS    IN   THE    VOSGE«. 

by  the  reasonable  supposition  that  the  plants  among  which 
they  have  flowed  have  deprived  them  of  a  portion  of  their  en- 
riching matter. 

But,  in  the  same  neighborhood,  it  has  been  often  observed 
that  waters  from  natural  springs  which  are  perfectly  alike  in 
appearance,  yet  differ  remarkably  in  their  value  for  irrigation. 
Such  is  the  case  among  the  mountains  of  the  Vosges,  where  ir- 
rigation is  much  attended  to.  The  same  quantity  of  water, 
from  two  neighboring  springs,  for  example,  employed  on  two 
adjoining  meadows  of  similar  quality,  in  1848,  gave  of  hay  per 
acre — 

1st  Cutting.        2d  Cutting.  Total. 

Good  spring,     .        .        58  cwt.  24  cwt.  82  cwt 

Bad  spring,       .        ,        14   . .  7  J  . .  21 J  . . 

Or  the  good  spring  produced  nearly  four  times  as  much  hay  as 
the  bad  one. 

A  chemical  examination  of  the  waters  of  the  two  springs 
satisfied  the  experimenters  (Chevandier  and  Salve  tat)  that  this 
difference  was  not  due,  either, 

a.  To  the  quantity  or  kind  of  the  gases  which  the  two  waters 
held  in  solution  ;  nor 

b.  To  the  quantity  or  kind  of  the  mineral  matters  in  which 
both  wei'e  nearly  equally  rich  ;  nor 

c.  To  the  quantity  of  organic  matter,  of  which  the  bad 
water  in  reality  contained  the  most  ;  nor 

d.  To  the  absolute  quantity  of  nitrogen  contained  in  this  or- 
ganic matter — for  the  bad  water  actually  spread  the  larger 
quantity  over  the  soil  ;  but 

c.  To  the  circumstance  that  the  organic  matter,  though 
smaller  in  quantity,  was  richer  in  nitrogen.  It  contained  six 
per  cent  of  this  constituent,  while  that  of  the  poor  water  con- 
tained only  two  per  cent. 

This  result  is  in  entire  consistency  with  all  I  have  stated  on 
the  subject  of  manures — of  the  necessity  of  nitrogen  to  the 
growth  of  plants  (p.  51,; — of   the  tendency  of  such  as  are 


ENGLISH   AND   INDIAN   RIVERS.  211 

rich  iu  nitrogen  especially  to  promote  growth — and  of  the  in- 
fluence of  organic  matters,  rich  in  nitrogen,  in  enabling  plants 
to  work  up  the  mineral  and  other  ingredients  in  a  mixed  ma- 
nure or  in  the  soil,  (p.  129,)  which  may  happen  to  be  within 
their  reach.* 

*  The  following  extracts  in  connection  with  waters  good  and  had  for  irri- 
gating, will  interest  tki->  reader : — 

"  There  are  two  brooks  on  this  estate,  Delamere,  (the  property  of  'G. 
Wilbraham,  Esq.,) — one  a  clear  white  water,  the  other  brown — both  of 
which  abound  in  trout,  and  on  each  there  are  irrigated  meadows.  In  the 
former  stream  the  trout  are  large ;  in  the  latter  small,  and  never  grow  be- 
yond a  certain  size.  The  meadows  watered  by  the  former  are  green,  lux- 
uriant, and  productive ;  those  of  the  latter  comparatively  barren.  It  is 
supposed  that  the  pernicious  effects  of  the  brown  stream  are  occasioned  by 
passing  through  peat  or  some  mineral  substance ;  but  the  cause  has  never 
been  satisfactorily  demonstrated." — Mr.  Palin,  "  On  the  Agriculture  of 
Cheshu-e,"  in  Royal  Agricultural  Journal,  of  the  Koyal  Agricultural  Soci- 
ety, vol.  V.  p.  105. 

"  On  the  property  of  the  Earl  of  Caernarvon,  near  Exmoor,  there  are 
four  streams: — the  Hudson,  containing  excellent  trout,  and  making  su- 
perior water-meadows ;  the  Exe,  inferior  in  the  quahty  of  the  fish,  and  less 
beneficial  to  grass ;  the  Barle,  worse  again  in  each  respect ;  and  lastly,  the 
Danes'  brook,  containing  no  fish  at  all,  and  itsolfj  as  I  am  informed,  poison- 
ous to  grass  land.  The  variation  of  their  color  confirms  Mr.  Palin's  opinion 
that  these  differences  are  owing  to  the  presence  of  peat." — Ph.  Puset, 
ibid.  Note. 

As  a  pendent  to  these  home  cases,  I  add  the  following  regarding  a 
foreign  river  in  different  parts  of  its  course  : — 

"  I  ought  to  mention  of  the  Tochee,  that  so  long  as  it  remains  in  Bunnoo, 
its  waters  are  used  both  for  irrigatioii  and  household  purposes,  and  I  never 
heard  any  complaint  of  it  in  either  of  these  departments.  But,  changing 
its  qualities  with  its  name,  in  Merwut,  the  Groombeeluh,  as  it  is  now  called, 
is  deemed  useless  for  agriculture ;  and  though  habit  enables  the  natives  to 
drink  it  with  impunity,  it  is  very  injurious  to  strangers,  producing,  after  a 
few  days,  and  sometimes  hours,  great  pain  and  inflammation." — A  Tear  on 
the  Punjab  Frontier  in  1848-49,  by  Major  Herbekt  B.  Edwards.  VoL  i 
p.  68. 


CHAPTER  XXI 

The  products  of  vegetation. — Influence  of  different  manures  on  tbo  quan* 
tity  of  a  corn  crop. — Average  composition  of  the  grain  of  wheats  and 
influence  of  climate  upon  that  composition. — Influence  of  manure  on  the 
proportion  of  gluten  and  yield  of  flour. — Experiments  of  Mr.  Burnet. — 
Composition  of  the  oat,  and  influence  of  variety  on  its  composition  and 
nutritive  quality. — Composition  of  barley,  and  influence  of  circumstances 
on  its  sprouting,  melting,  and  feeding  properties. — Composition  of  rice, 
maize  (Indian  corn),  and  buckwheat. — Composition  of  the  bean,  the  pea^ 
and  other  leguminous  seeds. — Composition  of  oily  seeds,  and  nuts,  and  of 
the  acorn. — Relation  of  the  quality  of  the  soil  to  the  quality  of  our  com 
crops. 

Thk  first  object  of  the  practical  farmer  is,  to  reap  from  his 
land  the  largest  possible  return  of  the  most  valuable  crops, 
without  permanently  injuring  or  exhausting  the  soil.  With 
this  view  he  adopts  one  or  other  of  the  methods  of  treatment 
above  adverted  to,  by  which  either  the  physical  condition  or 
the  chemical  composition  of  the  soil  is  altered  for  the  better 

It  may  be  useful  to  show  how  very  much  both  the  quantity 
and  the  quality  of  a  crop  is  dependent  upon  the  mode  in  which 
it  is  cultivated  and  reaped,  and  how  much  control,  therefore, 
the  skilful  agriculturist  really  possesses  over  the  ordinary  pro- 
ductions of  nature. 

SECTION  I, OF  THE  INFLUENCE   OF   MANURE   ON   THE   QUANTITY   OF 

THE   WHEAT   AND   OTHER   CORN   CROPS. 

Every  one  knows  that  some  soils  naturally  produce  mncli 

larger  returns  of  wheat,  oats,  and  barley  than  others  do,  and 

"that  the  same  soil  will  produce  more  or  less  according  to  the 

mode  in  which  the  land  has  been  prepared — by  manure  or 


INFLUENCE   OF   MANURE,  219 

otherwise — for  the  reception  of  the  seed.  The  following  table 
shows  the  effect  produced  upon  the  quantity  of  the  crop  by 
equal  quantities  of  different  manures  applied  to  the  same  soil, 
sown  with  an  equal  quantity  of  the  same  seed  : — 

Return  in  bushels  from  each  bushel  of  seed. 


Manure  applied. 

Wheat. 

Barley. 

Oats. 

Rye. 

Blood,       . 

14= 

16 

12J 

14 

Nightsoil, 

—   , 

13 

14i 

13J 

Sheep's  dung, 

12 

16 

14 

13 

Horses'  dung, 

10 

13 

14 

11 

Pigeons'  dung. 

— 

10 

12 

9 

Cows'  dung, 

1 

11 

16 

9 

Vegetable  manure, 

3 

7 

13 

6 

"Without  manure, 

— 

4 

5 

4 

It  is  probable  that  on  different  soils  the  returns  obtained  by  the 
use  of  these  several  manures  may  not  be  uniformly  in  the  same 
order,  yet  it  will  always  be  found  that  blood,  nightsoil,  and 
sheep,  horse,  and  pigeons'  dung,  are  among  the  most  enriching 
manures  that  can  be  employed.     (See  table  in  pp.  213,  214.) 

It  is  a  practical  fact,  bearing  upon  this  point,  that  in  some 
parts  of  Bedfordshire,  high-farming  causes  barley  to  run  to  straw, 
to  the  injury  of  the  corn  ;  while,  on  the  contrary,  the  wheat  in- 
creases in  yield  with  higher  cultivation.* 

Two  facts  will  particularly  strike  the  practical  man  on  look- 
ing at  the  above  table. 

1.  That  exclusive  of  blood,  sheep's  dung,  in  these  experiments, 
gave  the  greatest  increase  in  the  barley  crop.  The  favorite 
Norfolk  system  of  eating  off  turnips  with  sheep  previous  to 
barley,  besides  other  benefits  which  are  known  to  attend  the 
practice,  may  possibly  owe  part  of  its  acknowledged  utiUty  to 
this  powerful  action  of  sheep's  dung  upon  the  barley  crop.  Still, 
too  much  reliance  is  not  to  be  placed  on  such  special  results  till 
the  experiments  have  been  carefully  repeated. 

2.  The  action  of  cows'  dung  upon  oats  is  equally  striking,  and 
the  large  return  of  this  crop  (thirteen-fold)  obtained  by  the  us© 

*  Caibd's  English  Agriculture,  p.  451. 


280  AVERAGE   COMPOSITION    OF  THE    GEAIN    OF   WHEAT. 

of  vegetable  manure  alone,  may  perhaps  explain  why,  in  poorly 
farmed  districts,  oats  should  be  a  favorite  and  comparatively 
profitable  crop,  and  why  they  may  be  cultivated  with  a  certain 
degree  of  success  on  land  to  which  rich  manure  is  rarely  added. 
It  is  possible,  I  repeat,  that  results  different  from  those  re- 
corded in  the  above  table  may  be  obtained  by  a  careful  repeti- 
tion of  the  same  experiments  on  soils  of  different  kinds  and  in 
different  circumstances.  It  is  very  desirable,  therefore,  that  such 
experiments  should  be  undertaken,  accurately  conducted,  and 
carefully  recorded. 

SECTION    II. AVERAGE     COMPOSITION    OF    THE    GRAIN    OF    WHEAT, 

AND     INFLUENCE    OF     CLIMATE     ON     THAT     COMPOSITION. 

The  grain  of  wheat  consists,  on  an  average,  of 


Water, 

14.0 

Fatty  matter,      .... 

1.2 

Protein  compounds,      ) 
Gluten  and  albumen,  ) 

14.6 

Starch  and  dextrin. 

66.9 

Cellular  fibre. 

l.T 

Mineral  matter, 

1.6 

100 

This  average  composition  does  not  truly  represent  the  composi- 
tion of  our  British  and  European  varieties  of  wheat.  It  makes 
the  proportion  of  protein  compounds  rather  too  large.  Climate 
and  season  are  believed  to  influence  the  proportion  of  gluten,  so 
that  the  grain  of  warm  climates  and  hot  seasons  is  generally 
richer  in  this  ingredient.  Thus  four  varieties  gave  to  Peligot :— 


PECULIAR   QUAUTIES   OF   IMPORTED    WHEAT.  281 


Flemish. 

French. 

Polish.      Egyptian 
Grown  in  France. 

Water, 

14.6 

14.6 

13.2              13.5 

Fat, 

1.0 

1.3 

1.6               1.1 

Protein  compounds, 

10.7 

9.9 

21.5             20.6 

Starch,  &c. 

71.9 

74.2 

61.9             64.8 

Cellulose, 

1.8 

? 

?                   ? 

Mineral  Matter, 

? 

? 

1.9               ? 

100  100  100  100 

The  increased  proportion  of  protein  compounds  in  the  samples 
of  Polish  and  Egyptian  wheat  is  very  remarkable  ;  and  it  is  not 
less  interesting  that  they  had  been  grown  in  France  from  the 
foreign  seed.  This  latter  fact  illustrates — what  every  practical 
farmer  is  familiar  with — that  imported  seed  always  retains  for 
some  seasons  the  peculiar  qualities  which  distinguish  it  in  the 
country  from  which  it  is  brought.  It  is  not  to  be  supposed  that 
all  varieties  of  wheat  from  Poland  or  Egypt  contain  the  large 
proportion  of  gluten  found  by  Peligot  in  the  above  varieties, 
which  must,  I  believe,  be  regarded  as  very  rare  and  extreme 
cases.  An  increase  of  2  or  3  per  cent  in  the  protein  compounds 
is  the  most  that  can  reasonably  be  expected  in  Eastern  com- 
pared with  British  wheat  ;  and  even  this  is  by  no  means  con- 
stant, as  it  is  modified  by  season,  by  modes  of  culture,  and  b" 
other  causes. 

SECTION     III. — INFLUENCE     OF    THE    KIND     OF    MANURE    ON      THB 
PROPORTION  OF    GLUTEN  IN  WHEAT,  AND  ON  THE   YIELD  OF  FLOUR. 

-Among  these  other  modifying  causes  may  be  mentioned  the  kind 
of  manure  by  which  its  growth  is  assisted.  That  this  is  really  car 
pable  of  altering  the  proportion  of  gluten  contained  in  the  grain 
is  very  probable  ;  though  it  has  not  as  yet  been  experimentally 
established  that  it  is  capable  of  doing  so  in  a  very  great  degree. 

Another  influence  of  manure  upon  the  grain  of  wheat  appears 
less  uncertain — that  is,  the  proportion  of  fine  flour  which  the 


per  acre. 

from  the  grain. 

the  flour. 

In  bush. 

Per  cent. 

Per  cent 

31i 

16 

9i 

40 

66 

lOJ 

49 

63 

H 

49 

65 

94 

48 

64 

10 

282  COMPOSITION   OF  THE   OAT, 

grain  will  yield  when  sent  to  the  mill.   This  is  somewhat  striking- 
ly illustrated  by  the  following  experiment  : — 

The  same  variety  of  wheat,  toj^dressed  with  the  same  rich 
manure — sulphated  urine,  (p.  201,)  mixed  with  different  saline 
substances — and  grown  in  the  same  season  on  the  same  fields, 
gave  Mr.  Burnett  of  Gadgirth — 

Manure.  Produce        Fine  Flour        Gluten  iu 

No  manure,        .... 
Sulphated  urine  and  wood-ashes, 
Do.  and  sulphate  of  soda,  . 
Do.  and  common  salt, 
Do.  and  nitrate  of  soda,    . 

In  these  results  we  see,  first,  that  the  produce  of  fine  flour 
from  the  grain  is  very  different  in  the  different  samples  ;  and 
second,  that  the  rich  top-dressings  did  not  very  largely  increaoe 
the  proportion  of  gluten  in  the  flour. 

The  whole  produce  of  gluten  in  the  crop  was  increased,  be- 
cause the  crop  was  increased  in  quantity  ;  but  in  none  of  the  ex- 
periments was  the  percentage  of  gluten  largely  augmented.  A 
flour  peculiarly  rich  in  gluten  is  required — such  at  least  is  the 
prevailing  opinion — for  the  manufacture  of  macaroni  and  vermi- 
celli :  and  such  is  said  to  be  the  quality  of  the  grain  naturally 
produced  in  southern  Italy.  Further  experiments  are  required 
to  show  how  far,  by  what  means,  and  in  what  circumstances,  the 
percentage  of  protein  compounds  can  in  this  country  be  econo- 
mically increased  by  the  management  of  the  cultivator.* 

SECTION   IV, COMPOSITION    OF   THE    OAT,  AND   INFLUENCE   OF  VARI- 
ETY ON  ITS  COMPOSITION  AND  NUTRITIVE  QUALITIES. 

The  following  analyses  of  two  samples  of  Scotch  oats,  made 

♦  In  the  neighborhood  of  Kirkcaldy  wheat  is  said  to  be  poorer  after  early* 
lifted  than  after  ripe  potatoes.  Is  this  the  case  ? — and  if  so,  how  is  it  to 
be  explained  ? 


COMPOSITION  OF  OATS. 


283 


fii  my  laboratory  by  Professor  Norton,  will  show  the  relative 
proportions  in  which  the  several  constituents  exist  in  this  kind 
of  grain,  and  the  amount  of  variation  which  these  relative  pro- 
portions are  liable  to  undergo  in  this  country  in  different  vari- 
eties : — 

Composition  of  Oats,  dried  at  212  Fah.' 


Starch, 

Gum, 

Sugar, 

OU, 
'  Avenin,* 

Albumen,* 
[  Gluten, 

Husk, 

Ash, 


Potato 

Hopetoun 

Oats. 

Oats. 

65.60 

64.80 

2.28 

2.41 

0.80 

2'.58 

7.38 

6.97 

16.29 

*16.26 

2.17 

1.29 

1.45 

1.46 

2.28 

2.39 

2.60 

2.32 

100.85 


100.48 


The  united  percentage  of  the  three  varieties  of  protein  compounds 
(within  the  bracket)  in  the  oat  is  very  large  ;  and  hence  the 
very  nutritive  quality  of  this  grain.  But  the  quality  of  the  oat, 
like  that  of  wheat,  varies  with  the  soil,  the  climate,  the  manure, 
and  the  variety.  As  an  instance  of  the  latter,  I  may  mention 
that  the  hinds  in  many  parts  of  Scotland  live  only  on  oatmeal, 
of  which  they  are  allowed  two  pecks  each  a-week.  If  made  from 
potato  oats,  the  two  pecks  are  often  insufficient  ;  but  when  made 
from  the  common  Angus  oat,  this  quantity  is  frequently  more 
than  the  hind  can  consume. 

SECTION  V. INFLUENCE  OF  VARIETY  ON  THE  QUANTITY  OF  PRODUCE, 

AND  ON  THE  PROPORTION  OF  MEAL  YIELDED  BY  THE  OAT. 

The  quantity,  as  well  as  the  quality,  of  the  grain  of  the  oat 
yielded  by  the  same  soil  is  much  affected  by  the  variety  of  oat 
which  is  sown.    The  proportion  of  meal  yielded  by  an  equal 


See  page  47. 


284 


COMPOSITION  OF  BAKLET. 


weight  of  the  grain  is  also  materially  affected  by  the  variety 
This  is  shown  by  the  following  table  of  the  results  obtained  by 
Mr.  Hay  from  eight  different  varieties  of  oats  well  known  in 
Scotland.  The  experiment  was  made  in  the  year  1850,  upon  a 
thorough  drained  field  of  stiff  cold  clay  with  a  relentive  subsoil. 
All  the  varieties  were  sown  on  the  26th  and  27  th  of  March,  all 
reaped  between  the  20th  and  26th  August,  and  the  extent  of 
each  experimental  plot  was  three  quarters  of  an  imperial  acre. 


Variety. 

Produce. 

Meal  yielded 
by  100  lb. 
of  grain. 

I 

Grain. 

straw. 

Potato             oat,    .... 

Sheriff              

Beriie               

Hopetoun        

Blainslie          

Sandy              

Early  Angus 

Barbachla        

1 

bush. 
69 
651 
55i 
56^ 
524 

48i 
45 

cwt. . 
62i 
55J 
55^ 
561 
60i 
48i 
451 
49 

lb. 

60i 

62i 

58 

60i 

511 

60 

55j 

60i 

The  differences  in  each  of  these  three  columns  are  very 
striking,  and  will  suggest  to  the  reader  many  interesting  con- 
siderations, to  which  space  does  not  permit  me  to  advert, 

I  only  add,  that  in  all  the  different  grains  we  cultivate  vari- 
ety is  found  to  affect  in  a  similar  manner  the  quantities  of  pro- 
duce reaped. 


SECTION  VI. — OF  THE  AVERAGE  COMPOSmON   OF   BARLEY. 

The  Scotch  oat  is  the  most  nutritious  of  our  homegrown 
grains.  Among  the  ancients,  barley  was  highly  esteemed  for 
its  feeding  qualities  The  Greeks,  Egyptians,  and  Hebrews 
made  much  use  of  it,  and  the  wrestlers  and  gladiators  ate  only 
barley  bread  ;  hence  they  were  caWed  hordearii*  It  is  still  re- 
cognised in  this  country  as  possessed  of  great  feeding  power, 
*  Puorr,  Book  xviii. 


MALTING   QUALITIES    OF   BARLEY.  285 

though  the  higher  price  obtained  for  samples  which  malt  well 
has  thrown  somewhat  into  the  shade  its  purely  nutritive  qual 
ities. 

The  average  composition  of  fine  barley  meal  is  nearly  as 
follows  : — 


"Water,       .        . 
Protein  compounds,   . 

Starch,  &c., 

14 
14 
68 

Fatty  matter, 
Mineral  matter, 

2 
2 

100 

The  above  is  exclusive  of  the  bran  separated  by  the  miller, 
which  forms  from  10  to  18  per  cent  of  the  weight  of  the  grain. 
It  shows  the  flour  to  be  very  nutritious,  containing  14  per  cent 
of  the  protein  or  flesh-forming  constituent,  while  fine  wheateu 
flour  rarely  contains  more  than  10  per  cent. 

SECTION   VIII. — ^INFLUENCE   OF   CIRCUMSTANCES   ON   THE   SPROUTING, 
MALTING,    AND    FEEDING   QUALniES    OF    BARLEY, 

1°.  Malting  qualities. — The  malting  of  barley  is  known  to  be 
affected  by  various  circumstances.  Unless  the  grain  be  dry,  it 
does  not  sprout  readily,  and  hence  it  is  customary  for  maltsters 
to  sweat  their  barley  on  the  kiln  before  malting  it.  The  grain 
should  also  be  so  uniform  in  ripeness  as  to  sprout  uniformly,  so 
that  no  part  of  it  may  be  beginning  to  shoot  when  the  rest  has 
already  germinated  sufficiently  for  the  maltster's  purpose.  On 
this  perfect  and  uniform  sprouting  of  the  whole  depends  in  some 
degree  the  swelling  of  the  malt,  which  is  of  considerable  conse- 
quence to  the  manufacturer. 

The  uniformity  of  sprouting  depends  sometimes  on  the  mode 
of  husbandry  practised  where  it  is  grown.  Thus  when  barley  is 
taken  after  turnips,  if  the  land  be  merely  cross-ploughed,  the  ma- 
nure which  had  been  laid  in  the  turnip  drills  will  remain  in  lines 
along  the  field  where  the  turnips  had  grown,  and  the  barley  along 


286  FEEDING   QUALITIES    OF    BARLEY. 

those  lines  will  ripen  first.  But  if  the  land  be  ploughed  diagoib' 
ally,  the  manure  will  be  equally  spread  and  the  barley  nourished 
and  ripened  equally,  and  thus  it  will  be  likely  to  sprout  uniform- 
ly also. 

But  the  malting  quality  of  the  grain,  which  is  of  more  con- 
sequence to  the  brewer  and  distiller,  is  understood  to  be  modi- 
fied chiefly  by  the  proportion  of  gluten  which  the  barley  contains. 
That  which  contains  the  least  gluten,  and,  therefore,  the  most 
starch,  is  supposed  to  malt  the  most  easily  and  the  most  completely 
and  to  yield  the  strongest  beer  or  spirit  from  the  same  quantity 
of  grain.  Hence  the  preference  given  by  the  brewer  to  the  malt 
of  particular  districts,  even  where  the  sample  appears  otherwise 
inferior.  Thus  the  brewers  on  the  sea-coast  of  the  county  of 
Durham  will  not  purchase  the  barley  of  their  own  neighbor- 
hood, if  Norfolk  grain  can  be  had  at  a  moderate  increase  of  price. 
But  that  which  refuses  to  malt  well  in  the  hands  of  the  brewer, 
will  cause  pigs  and  other  stock  to  thrive  well  in  the  hands  of  the 
feeder,  and  this  is  the  chief  outlet  for  the  barley  which  the  brew- 
er and  distiller  reject. 

2°.  Feeding  qualities. — So  far  as  a  practical  deduction  can  be 
drawn  from  the  experiments  hitherto  made  in  regard  to  the 
effects  of  different  manures  upon  the  proportion  of  gluten  in 
barley,  it  would  appear  that  the  larger  the  quantity  of  cows' 
dung  contained  in  the  manure  applied  to  barley  land — in  otlier 
words,  the  greater  the  nuviber  of  stock  folded  about  the  farmyard, 
the  more  likely  is  the  barley  to  be  such  as  will  bring  a  high  price 
from  the  brewer. 

The  folding  of  sheep  appears  to  produce  a  larger  return  from 
the  barley  crop,  and  the  folding  of  cattle  to  give  grain  of  a  better 
quality.  These  points  also,  however,  require  to  be  elucidated 
by  more  careful  experiment.  Such  statements  stand  in  our 
books  at  present  rather  as  guesses  at  the  truth,  than  as  deduc* 
tions  from  rigorously  made  observations. 


COMPOSITION    OF    BEAN,    PEA,    &C. 


287 


BKCTION   VIII. COMPOSITION   OP  EYE,  RICE,  MAIZE  ^^ INDIAN  CORN), 

AND    BUCKWHEAT. 

These  four  species  of  grain  contain  respectively,  when  dried  at 
212°  Fahr.,  of— 


Starch,  &c., 

Protein  compounds,  .     . 
Fatty  matter,    .... 

Husk, ) 

Mineral  matter,      .     .    ) 

Rye. 

Rice. 

Maize. 

Buckwheat. 

■78.0 

12.5 

3.5 

6.0 

8'7.4 
7.5 
0.8 
3.4 
0.9 

11.6 

12.3 

9.0 

5.9 

1.2 

60.6 
10.7 

0.4 
26.0 

2.3 

100 

100 

100 

100 

These  numbers,  it  will  be  understood,  are  liable  to  variation  in 
different  samples  ;  especially  the  quantity  of  protein  compounds 
in  rye  varies,  and  that  of  the  fatty  matter  or  oil  contained  in 
Indian  corn.  In  some  varieties  of  the  latter  grain  this  oil  is 
only  2  to  3,  in  others  as  much  as  9,  per  cent  of  the  dry  cone. 

In  their  natural  undried  state  they  all  contain  14  to  15  per 
cent  of  water.  It  will  be  seen  that,  in  so  far  as  that  the  protein 
or  muscle-forming  ingredients  are  concerned,  rice  is  the  least, 
and  rye  and  maize  the  most  nutritious  of  these  four  varieties  of 
grain. 


SECTION  IX. COMPOSmON    OF    THE    BEAN,    THE    PEA,    AND    OTHER 

LEGUMINOUS  SEEDS. 

The  bean,  pea,  lentil,  vetch,  &c.,  are  distinguished  from  white 
corn  by  the  large  proportion  of  protein  compounds  they  contain, 
and  their  consequently  greater  nutritive  power.  They  resemble 
each  other  very  much  in  composition  ;  and  in  the  state  of  dry- 
ness in  which  they  are  generally  brought  to  market,  as  field 
crops,  they  consist  of  about 


288  COSIPOSITION    OF    OILY    SEEDS   AND   NCTS. 


"Water,        .        .        •        • 

Starch  and  sugar, 

Protein  compounds,  (legumin,) 

Fatty  matter, 

Husk, 

Mineral  matter  . 


14 

48 
24 

2 
10 

2 

100 

The  proportion  of  husk  varies  ;  the  pea,  which  contains  10  per 
cent,  having  generally  a  thinner,  and  the  bean  a  thicker  skin. 
The  proportion  of  protein  compounds  varies  from  20  to  as  high 
as  30  per  cent  ;  and  according  to  experiment,  the  kind  of  ma- 
nure employed  materially  influences  this  proportion.  Manures 
rich  in  nitrogen  cause  it  to  increase.  It  is  also  an  interesting 
fact  that  the  young  legumes,  when  just  beginning  to  form  in  the 
shell,  are  exeedingly  rich  in  protein  compounds.  The  very 
young  pea,  for  example,  contains  as  much  as  48  per  cent  ;  while, 
as  the  above  table  shows,  the  ripe  pea  rarely  contains  more 
than  24  per  cent  (p,  61.) 

The  kind  of  protein  compound  which  exists  in  these  grains 
possesses  peculiar  chemical  properties,  and  has  been  called  le- 
gumin, (p.  47  ;)  but  its  nutritive  qualities  are  believed  to  be 
very  much  the  same  as  those  of  gluten  and  albumen. 

SECTION   X. COMPOSITION     OF    THE    OILY    SEEDS    AND    NUTS,     AND 

OF   THE    ACOKN. 

Many  seeds,  like  those  of  flax  and  rape,  contain  a  much  larger 
quantity  of  oil  than  the  kinds  of  corn  which  are  usually  em- 
ployed as  food  for  man.  The  same  is  the  case  with  nuts.  From 
the  kernels  of  the  walnut,  for  example,  and  from  those  of  the  sweet 
almond,  upwards  of  half  their*  weight  of  oil  can  often  be  extracted. 

1.  Linseed  and  linseed  cake. — Linseed  contains  from  20  to  30 
per  cent  of  oil.  A  large  proportion  of  this  is  squeezed  out  in 
the  oil  mills,  and  sold  under  the  name  of  linseed  oil.  The  cake 
or  residue  which  remains,  still  contains  a  considerable  proportion 
of  oil  ;  and,  as  it  is  very  nutritive,  is  extensively  employed  in 


COMPOSITION   OP  THE   ACORN.  289 

the  feeding  of  cattle.  The  relative  values  of  the  seed  and  the 
cake  for  feeding  purposes,  and  the  value  of  both  compared  with 
other  kinds  of  food,  is  shown  very  nearly  by  the  following 
table  : — 


Composition  of 

Linseed.        Linseed  cake. 

"Water, 

9 

10 

Protein  corapoimdg,    . 

19 

22 

Starch,  &c., 

34 

39 

on,           ... 

25 

12 

Husk, 

8 

9 

Saline  mineral  matter, 

5 

8 

100  100 

.  Both  seed  and  cake,  therefore,  are  very  nutritious  ;  and  even 
the  pressed  cake  still  contains  more  fatty  matter  than  Indian 
corn,  some  varieties  of  which  contain  as  much  as  9  per  cent. 

What  is  called  starch  in  the  above  analyses  is,  in  reality,  a 
kind  of  mucilage  or  gum,  which  dissolves  readily  in  water,  but 
serves  the  same  purposes  as  starch  in  the  feeding  "of  animals. 

2.  Rape  cake  is  about  of  equal  nutritive  value  with  linseed 
cake,  but  is  often  refused  by  cattle  on  account  of  its  hot  and 
acrid  taste  :  this  repugnance,  however,  may  be  overcome  by 
mixing  the  crushed  cake  with  a  small  quantity  of  molasses,  or, 
by  boiling  it  into  a  jelly  with  one-third  of  bean-meal,  and  making 
this  into  a  mpss  with  cut  straw  or  hay.  Sheep  eat  it  readily 
when  fed  upon  cabbage,  and  if  kept  upon  other  green  food  they 
soon  become  accustomed  to  it,  if  copiously  supplied  with  water 
The  lower  market  price  of  rape  cake  makes  a  knowledge  of 
these  circumstances  of  money  value  to  the  practical  feeder. 

3.  Nuts  resemble  the  oily  seeds  in  their  composition  ;  and 
hence  nut-cakes  approach  linseed  cake  in  value  as  a  food  for 
cattle. 

4.  The  acorn  is  also  very  nutritious,  though  it  does  not  con- 
tain much  fatty  matter.  As  it  falls  ripe  from  the  tree  it  consists 
of— 

18 


too  INFLUENCE  OF  THE  SOIL  ON    JUB  CORN  CROPS 


"Water, 

Protein  compounds, 
Starch  and  sugar, 
Fatty  matter,        , 
Cellular  fibre, 
Mineral  matter,     . 


32 

15 

47 

3 

2 

1 

100 


Were  the  acorn  made  as  dry  as  the  bean  is  usually  sold, 
it  would,  weight  for  weight,  be  nearly  as  nutritive.  Hence  the 
fattening  of  pigs  when  turned  into  oak  forests,  the  use  of  the 
common  acorn  in  periods  of  famine  in  many  countries,  and  the 
constant  use  of  the  sweet  acorn,  (that  of  the  Quercus  gramwrUia 
of  Linnaeus,)  in  parts  of  Spain  and  Sardinia,  as  a  common  food 
of  the  people.  A  sweet  acorn  is  also  regularly  found  in  the 
North  African  markets  of  Constantine,  Bona,  and  Algiers. 

The  acorn  is  remarkable  for  containing  as  much  as  7  per  cent 
of  sugar,  of  which  a  small  portion  is  sugar  of  milk.  Could  the 
bitter  astrmgent  substance,  which  gives  our  common  acorns  their 
unpleasant  taste,  be  readily  extracted,  it  might  become  an  ac- 
ceptable article  of  food  in  every  country. 

SECTION  XI. — ^INFLUENCE  OF  THE   CONDITION    AND   QUALITT  OF  THB 
SOIL  ON  THE  QUALITT  OF  OUR  CORN  CROPS. 

We  have  already  shown  that  the  quantity  of  the  crop  is  ma- 
terially affected  by  the  character  of  the  soil,  but  the  quality  of 
the  produce  is  no  less  affected  by  the  same  cause.    Thus — 

1.  Barky. — ^The  varying  quality  of  this  grain  raised  in  different 
localities  is  familiar  to  every  farmer.  On  stiff  clays,  barley  may 
yield  a  greater  produce,  (North  Hampshire,)  but  it  is  of  a 
coarser  quality.  On  light  chalky  soils  it  is  thin-skinned,  rich  in 
color,  and,  though  light  in  weight,  well  adapted  for  malting; 
while  on  loamy  lands  and  on  sandy  marls  it  assumes  a  greater 
plumpness,  yet  still  retains  its  malting  quality.* 

*  See  p.  96,  on  the  growth  of  the  Ware  malL 


PECULIARITIES   OF   THE    PEA   AND    BEAN.  291 

2.  Wheat. — Similar  differences  affect  the  same  yariety  oi  wheat 
when  grown  upon  different  soils.  In  a  previous  section  it  was 
stated  that  the  quantity  of  gluten  contained  in  wheat  is  believed 
to  vary  with  the  climate,  and  in  some  degree  also  with  the  ma- 
nure applied  to  the  land  ;  but  a  similar  variation  occurs  on  unhke 
soils,  when  manured,  or  otherwise  treated  in  every  respect  alike. 
The  miller  knows  by  experience  the  relative  qualities  of  the  wheat 
grown  on  the  several  farms  in  the  neighborhood  of  his  mill,  so 
that  even  when  his  eye  can  detect  no  difference  of  quality  be- 
tween two  samples,  a  knowledge  of  the  places  where  they  were 
grown  enables  him  to  decide  which  of  the  two  it  will  be  most  for 
his  interest  to  buy. 

3.  The  oat  varies  in  quality  likewise  with  the  soil  on  which 
it  is  grown.  The  meal  made  from  oats  grown  upon  clay  land  is 
the  best  in  quality,  is  the  thriftiest,  keeps  the  longest,  and  gen- 
erally brings  the  highest  price. 

I  lately  visited  a  farm  in  Forfarshire,  part  of  which  consisted 
of  a  sharp  gravelly  soil  on  a  slope,  and  part  of  flat  boggy  land, 
resting  on  marl.  Oats  were  usually  grown  on  both  soils,  and  I 
asked  what  difference  the  tenant  observed  in  the  quality  of  the 
grain  he  obtained  from  each.  "  In  appearance,"  he  answered, 
"  there  is  no  difference  ;  I  could  take  the  samples  to  market,  and 
get  the  same  price  for  each.  If  I  wanted  them  for  seed,  I  would 
buy  either  of  them  indifferently  at  the  same  price  ;  but  for  meal 
for  my  own  eating,  I  would  give  two  shillings  a  boll  more  for 
the  oats  of  the  sharp  land.  The  sharp  land  meal,"  he  added, 
"  gives  a  dry  knotty  brose  and  a  short  oat  cake ;  that  from  the  bog 
land  may  do  for  porridge,  but  it  makes  bad  soft  brose  and  a  tough 
cake." 

4.  Rye  also  flourishes  upon  light  and  sandy  soils  in  genera* 
but  when  grown  upon  sandy  marls  it  is  found  (in  Germany)  to 
yield  much  brandy. 

5.  The  pea  and  the  bean  are  distinguished  by  similar  peculiarities, 
when  grown  in  light  and  in  heavy  soils.  There  are  certain  spots 
in  the  neighborhood  of  all  large  towns,  which  are  known  to 


292  BOILING  AND  PIG  PEAS. 

produce  the  best  boiling  peas, — such  as  boil  soft  and  mealy. 
Thus  the  gravelly  slope  of  Hopwas  Hill,  near  Tamworth,  on  the 
Lichfield  road,  grows  the  best  sidder  or  boiling  green  peas  for 
the  Birmingham  market  ;  the  Yale  of  Tamworth  in  general 
growing  only  pig  peas — hard  boilers  used  only  for  feeding.  Lime 
and  gypsum  are  said  by  some  to  impart  the  boiling  quality,  while 
by  others  exactly  the  reverse  is  stated.  No  doubt  the  different 
results  are  owing  to  differences  in  the  soils  upon  which  the  seve- 
ral experiments  were  made. 

It  is  a  remarkable  circumstance,  that  on  the  London  corn 
exchange,  the  dealers  seldom  buy  British  peas  without  first 
sending  a  sample  to  be  boiled, — while  foreign  peas  are  gene- 
rally bought  without  any  trial.  They  are  almost  invariably 
boilers.  For  split  peas,  used  in  making  soups  and  pease-meal, 
it  is  obvious  that  this  boiling  quality  is  of  great  importance. 

The  explanation  of  all  these  differences  is,  to  a  certain  extent, 
simple.  The  relative  proportions  of  gluten  and  starch  in  all 
vegetable  juices,  and  seeds,  is  variable.  The  plant  is  fitted  to 
flourish,  to  live  in  a  comparatively  healthy  manner,  and  to  per- 
form all  its  natural  functions,  although  the  supply  of  those 
kinds  of  food  out  of  which  its  gluten  is  formed  be  greater  or 
less  within  certain  limits  ;  but  the  boiling,  feeding,  malting,  or 
distilling  qualities  of  its  stems,  seeds,  or  roots  will  be  materially 
affected  by  variations  in  this  supply. 

Again,  the  proportion  of  gluten  seems  to  be  dependent  upon 
the  quality  of  the  soil,  not  only  because  the  nitrogen  it  con- 
tains is  chiefly  imbibed  by  the  roots  of  the  plant,  but  because 
this  gluten  is  always  associated  with  a  certain  small  quantity 
of  sulphur,  phosphorus,  and  earthy  matter,  which  can  only  be 
derived  from  the  soil.  Where  these  elements  abound  in  the 
neighborhood  of  the  roots,  the  plant  may  produce  much  glu- 
ten ;  where  they  are  absent,  it  may  not  ;  so  that  the  feeding 
and  other  important  qualities  of  the  plant  depend  no  less  upon 
the  presence  of  sulphur  and  phosphorus  in  the  soil,  than  upon 


CAUSE  OP  THESE  DIFFERENCES.  293 

that  of  any  of  the  so-called  organic  elements  of  which  its  se- 
veral parts  are  principally  made  up. 

Still  it  must  be  borne  in  mind,  that  these  explanations  of  the 
differences  observed  on  the  corn  exchange,  and  by  the  miller, 
are  as  yet  hypothetical.  The  causes  stated  may  produce  the 
effects  actually  observed,  but  it  has  not  been  proved,  by  ana- 
lytical and  other  experiments,  that  they  really  do  produce  them. 
Mere  age  induces  changes  in  the  qualities  of  grain,  such  as  I 
have  described,  which  the  isiiller  values  and  is  willing  to  pay  for. 


CHAPTER  XXII. 

Average  composition  of  the  potato,  turnip,  mangold-wurtzel,  and  carrot- 
Influence  of  soil,  variety,  manure,  &c.,  on  the  quahty  of  the  potato  and 
the  quantity  of  starch  it  contains. — Influence  of  soil,  season,  variety,  and 
manure  on  the  composition  and  feeding  properties  of  the  turnip. — Com- 
position of  the  cabbage,  cauliflower,  mushroom,  turnip-top,  and  of  hay, 
straw,  and  the  leaves  of  trees. — Composition  of  fruits,  and  the  effect  of  soil 
upon  their  quahty  and  flavor. — Relative  quantities  of  starch  and  gluten 
contained  in  our  usually  cultivated  crops. — Quantity  of  oil  or  fat  in  grain, 
root,  and  hay  crops. — Absolute  quantity  of  food  yielded  by  an  acre  ol 
land  under  different  crops. 

SECTION  I. ^AVERAGE    COMPOSITION    OF   THE   POTATO,    TURNIP,   MAN- 
GOLD-WURTZEL,   AND    CARROT. 

1.  The  turnip  tribe  diflfers  from  the  potato  in  two  principal 
points. 

a.  In  the  quantity  of  water  they  respectively  contain.  In 
the  potato  this  forms  three-fourths,  but  in  the  turnip  nine-tenths, 
of  the  whole  weight,  when  taken  from  the  ground  :  or  they 
consist  of — 

Potato.    Turnip. 
Water,  ....        75  91 

Dry  nutritive  matter,  .  .25  9 

100  100 

h.  In  the  presence  of  starch  in  the  potato,  while  the  turnip 
contains  in  its  stead  a  substance — pectose  or  pectic  acid — which 
contains  more  oxygen  than  starch,  but  serves  the  same  pur- 
poses in  the  nutrition  of  animals,  (p.  44.) 

2.  The  dry  nutritive  matter  of  the  potato  and  turnip  con- 
tains, on  an  average,  about —  ; 


IMPORTANCE  OF  THE  POTATO.  295 


Potato. 

Turnip. 

Starch  or  pectose, 

62 

16 

Sugar  and  gum, 

15 

66 

Protein  compounds, 

9 

IS 

Fatty  matter, 

1 

2 

CeUuIar  fibre, 

9 

7 

Mineral  matter, 

4 

6 

100  100 

This  table  shows  also  that  the  turnip  contains  more  sugar 
than  the  potato,  and  is  richer  also  in  protein  compounds.  Hence 
the  advantage  derived  from,  and  the  preference  generally  given 
to  it,  in  the  feeding  of  stock. 

3.  The  dry  matter  of  the  mangold-wurtzel  and  the  carrot 
resembles  iu  composition  that  of  the  turnip.  Some  varieties  of 
these  roots  contain  still  more  sugar.  They  likewise  surpass  the 
turnip  in  their  per-centage  of  dry  nutritive  matter.  This,  in 
the  three  roots,  is  nearly  as  follows  : — 

Turnip.  Mangold.  Carrot. 

Dry  nutritive  matter,        8  to  12  15  14  to  20 

Water,  .  .      92  to  88  85  86  to  80 

100  100  100 

Hence  the  generally  more  nutritive  quality  of  the  two  latter 
roots,  weight  for  weight. 

gECTION   II. ^INFLUENCE   OF   SOIL,    VARIETY,    DEGREE   OF  RIPEKESS, 

KIND   OF   MANURE,    AND    OTHER  CIRCUMSTANCES,    ON  THE  QUALITY 
OP   THE    POTATO,    AND   THE    QUANTITY   OP    STARCH   IT   CONTAINS. 

The  potato  is  a  crop  of  so  much  importance  in  this  country, 
that  it  may  be  interesting  to  introduce  a  few  more  detailed  re- 
marks in  regard  to  the  variations  which  the  quality,  and  especi- 
ally the  proportion  of  starch  contained  in  it,  has  been  found  to 
undergo. 

1,  Infiuence  of  soil. — It  is  familiarly  known  to  the  potato  grow- 
er, that  clay  soils  produce  waxy,  and  sandy  soils  mealy  potatoes- 


296  INFLUENCE   OF  VARIETY 

But  the  condition  of  the  land  also  exercises  a  material  in- 
fluence both  upon  their  growth  and  quality.  When,  for  example, 
potatoes  are  planted  in  rich  newly  broken-up  land,  they  run  up 
greatly  to  shaws  or  tops,  produce  generally  few  or  small  tubers, 
and  of  bad  eating  quality,  because  they  seldom  ripen  before  the 
frost  sets  in.  Thus  in  one  case  it  was  remarked  by  Mr.  Thompson, 
of  Kirby  Hall,  York,  that  black  kidmys  planted  on  such  a  soil 
seemed  quite  to  have  changed  their  character.  Instead  of  the 
fine  mealiness  for  which  they  are  usually  remarkable,  they  bore 
much  more  resemblance  to  a  piece  of  yellow  soap.  They,  how- 
ever, proved  excellent  seed,  and  in  the  wet  summer  of  1843 
showed  no  failures,  and  gave  a  capital  crop.  They  were  certain- 
ly not  ripe,  and  to  this  circumstance  Mr.  Thompson  ascribed  their 
badness  for  eating  and  their  goodness  for  seed. 

Again,  it  has  been  observed  that  the  quantity  of  starch  is 
larger  in  potatoes  which  are  grown  upon  land  long  in  arable 
culture  than  upon  such  as  is  newly  brought  into  cultivation  or 
broken  up  from  grass.  Thus  Mr.  Stirrat  states,  that  from  one 
peck  of  potatoes  grown  upon  laud  near  Paisley,  which  had  been 
almost  constantly  under  crop  for  the  last  thirty  years,  he  obtain- 
ed t  lb.  of  starch,  while  another  peck  grown  on  his  bleach-green, 
newly  broken  up,  gave  him  only  4  lb.* 

2.  Injliience  of  variety. — On  the  same  soil,  different  varieties 
produce  different  proportions  of  starch.  Thus,  in  1842,  Mr.  Flem- 
ing, of  Barochan,  obtained  from  four  varieties  of  potato  grown 
on  his  farm,  the  following  percentage  of  starch  : — 

Connaught  Cupa^  .  .  .  21  per  cent 

Irish  blacks,       .  .  .  ,  16^ 

White  Dons,       .  .  .  .  13        ... 

Red  Dons,  .  .  .  10|      ... 

These  differences  in  the  per-centage  of  starch  become  very 
striking  when  we  calculate  the  relative  quantities  per  acre  yielded 

*  See  the  Author's  Lectures  on  AgrictUiurai  Chemistry  and  Geology,  2d 
edit.  p.  981 


EFFECT  OF  MANURES. 


297 


by  these  varieties, 
spectively — 


Cups,         . 
Ecd  Dons, 
White  Dons, 


Thus  under  similar  treatment  they  gave  re- 


Produce  per  acre. 
Of  potatoes.        Of  starch. 
13  j  tons.         2.9  tons. 
14i  1.5 

18J  2.4 


So  that  the  lightest  crop  gave  the  most  starch.  Though  jive  ton 
an  acre  heavier,  the  crop  of  white  Doris  gave  half  a  ton  less  starch 
than  the  Connaught  Cups. 

3.  Effect  of  manures.  — I  have  already  mentioned  the  alleged 
influence  of  sea-weed,  (p.  169,)  and  of  skin  parings,  (p.  162,)  in 
making  potatoes  waxy.  It  is  not  so  surprising,  therefore,  that 
the  kind  of  manure  employed  should  affect  in  a  sensible  degree 
the  proportion  of  starch  yielded  by  the  potato.  Thus  Mr.  Flem- 
ing found  his  potatoes,  raised  with  different  manures  in  1843,  to 
give  the  following  per-centage  of  starch  : — 


1.  Cups  with  dung  alone,  gave 
and  guano, 

2.  White  Dons  with  guano  alone, 
and  dung,    - 

3.  Rough  reds  with  guano  alone, 
and  dung,    - 

4.  Perth  reds  with  guano  alone, 
and  dung    - 


Per  cent. 
14.5  of  starch. 
14-4 

9.0 
10.2 

15.7 
17.1 

15.3 
15.5 


These  experiments  show,  frst,  that  in  so  far  as  the  proportion 
of  starch  is  concerned,  either  dung  alone,  or  half  guano  and  half 
dung,  may  be  used  with  equal  advantage.  The  experiment  upon 
the  Cups  shows  this.  Second,  that  a  mixture  of  dung  and  guano 
is  in  this  respect  better  than  guano  alone.*     All  the  other  trials 

*  This  arises  from  the  tendency  of  the  potato  to  rush  up  to  stalk  when 
manured  with  guano  alone, — the  effect  of  the  guano  being  more  or  less 
exhausted  before  the  plant  reaches  maturity,  or  has  time  to  form  its  tubera. 
When  mixed  with  dung,  the  latter  carries  on  the  growth  which  the  former 
may  have  left  unfinished. 
IS* 


298.  INFLUENCE   OF   SOIL. 

show  this, — while  they  show  further,  also,  how  much  the  propor- 
tion of  starch  depends  upon  the  variety  of  potato  we  grow. 

These  varying  proportions  of  starch  are  of  much  moment  to 
the  practical  farmer  at  the  present  time,  when  potato  failures 
are  so  common, — inasmuch  as  the  certainty  of  the  growth  of  the 
potato,  when  used  as  seed,  appears  to  be  the  greater,  the  smaller  the 
per-centage  of  starch. 

4.  Effect  of  other  circumstances. — I  advert  briefly  to  three 
other  circumstances  which  affect  the  quantity  of  starch  con- 
tained in  the  potato. 

a.  The  effect  of  keeping  is  to  diminish  the  quantity  of  starch. 
Potatoes  which  in  October  yielded  readily  11  per  cent  of  starch, 
gave  in  the  following  April  only  14|  per  cent. 

In  connection  with  the  keeping  of  the  potato,  it  is  a  very 
interesting  fact,  that  the  epidermis  or  outer  covering  of  the 
skin  consists  of  a  thin  layer  of  cork,  without  visible  pores,  and 
through  which  water  passes  with  extreme  slowness.  Hence 
the  potato  can  be  kept  for  months  at  a  temperature  of  86° 
Fahrenheit,  without  losing  more  than  three  per  cent  of  its 
weight. 

b.  The  effect  of  frost  is  also  to  lessen  the  starch.  It  acts  chiefly 
upon  the  vascular  and  albuminous  part,  but  it  also  converts  a 
portion  of  the  starch  into  sugar,  hence  the  sweetish  taste  of 
frosted  potatoes. 

c.  The  heel  end  of  the  potato  contains  more  starch  than  the 
rose  end,  and  both  more  than  the  central  part.  Thus,  a  variety 
of  red  potato  which  yielded  21  per  cent  of  starch  from  the  heel 
end,  gave  me  only  16|  from  the  rose  end,  and  14  per  cent 
from  the  central  part. 

SECTION  III, INFLUENCE    OF  SOIL,    SEASON,  VARIETY,  AND  MANURE, 

ON  THE  COMPOSITION  AND  FEEDING  PROPERTIES  OF  THE  TURNIP. 

1.  Soil. — That  the  soil  has  an  influence  on  the  composition 
of  the  turnip  crop,  has  long  been  believed  by  the  practical  man. 


INFLUENCE   OF   MANURE.  299 

because  of  the  difference  in  the  taste  and  feeding  properties  of 
the  same  kinds  of  turnip  grown  on  different  fields  and  farms. 

The  chemical  nature  of  this  difference  has  lately  been  inves- 
tigated by  Dr.  Anderson,  His  analyses  of  turnips,  grown  in 
the  same  season  and  circumstances,  upon 

a.  The  heavy  alluvial  clay  of  the  Carse  of  Gowrie  ; 

h.  The  black  land  which  separates  the  clay  from  the  hill, 
and  there,  as  in  Lincolnshire,  skirts  the  slopes  ; 

c.  The  hill  land,  which  is  a  light  loam — 
showed  that  the  proportion  of  nitrogen  or  of  protein  compounds 
was  almost  always  greater  on  the  hill  land  than  on  either  of 
the  other  soils — sometimes  twicz  as  great.  The  turnips  of  the 
black  land  were  also  slightly  superior  in  this  respect  to  those 
of  the  clay.  This  result  of  analyses  fully  supports  that  of  prac- 
tical experience  in  the  feeding  of  stock. 

2.  Season. — The  same  analyses  have  confirmed  another  opin- 
ion of  practical  men,  that  the  turnips  of  different  seasons  differ 
in  their  nutritive  properties.  Thus,  in  1850,  the  turnips,  from 
all  the  varieties  of  soil  above  mentioned,  contained  a  smaller 
per-centage  of  protein  compounds  than  in  1849,  and  the  dif- 
ferences among  them  were  less.  The  proportion  of  phosphates 
was  also  considerably  less  in  the  turnips  of  1850. 

3.  Variety. — The  influence  of  variety  is  more  striking,  per- 
haps, on  the  turnip  than  upon  any  other  of  our  more  largely 
cultivated  crops.  The  swede  not  only  keeps  better  and  longer, 
but  is  also  sweeter  and  more  nourishing  than  the  white  globe 
or  yellow  turnip.  Hence  in  our  large  towns,  when  swedes,  as 
they  sometimes  do,  sell  for  30s.  a  ton,  the  yellow  will  bring 
only  25s.,  and  the  globe  turnip  18s. 

4.  Manure. — ^The  kind  of  manure  affects  the  quality  and 
feeding  properties  of  the  turnip.  According  to  the  experiments 
of  Mr.  Lawes,*  it  appears  that  where  a  field  is  in  a  condition 
to  produce  an  average  crop  of  turnips,  the   proportion  of  ni- 

*  Journal  of  tin  Royal  Agricultural  Society  of  England^  viiL  494. 


300  COMPOSITION   OF   THE   CABBAGE. 

trogen  in  the  crop — that  is  of  albumen  and  other  protein  com- 
pounds, which  are  very  nutritive — may  be  increased  by  the  ap- 
plication of  animal  or  other  manures  containing  nitrogen — such 
as  pigeons'  dung,  guano,  woolen  rags,  rape  cake,  the  salts  of 
ammonia,  nitrate  of  soda,  &c.  Mr.  Lawes  states,  that  by  the 
use  of  such  manures  the  proportion  of  this  valuable  ingredient, 
compared  with  what  is  contained  in  turnips  raised  by  farm- 
yard manure,  may  be  doubled.  This  result  has,  to  a  certain 
extent,  been  confirmed  by  the  more  recent  analyses  of  Scotch 
turnips  published  by  Dr.  Anderson.* 

It  is  desirable,  however,  that  the  results  of  experiments  in 
the  laboratory,  as  to  the  composition  of  the  crop,  should  be 
tested  by  after  experiments  with  the  same  turnips  in  the  actual 
feeding  of  cattle.  Such  experiments  are  difficult  of  execution, 
and  require  much  care,  but  they  are  necessary  to  the  attain- 
ment of  results  on  which  the  practical  man  can  be  requested 
confidently  to  rely. 

SECTION   IV. COMPOSITION  OF  THE    CABBAGE,    CAULIFLOWER,    MUSH- 
BOOM,  TURNIP-TOP,  HAY,  STRAW,  AND  THE  LEAVES  OF  TREES. 

1.  The  Callage  is  one  of  the  most  nutritious  crops  we  grow. 
Like  the  turnip,  it  contains  a  large  proportion  of  water — about 
89  per  cent ;  but  the  dry  matter  of  the  cabbage  is  much  more 
rich  in  protein  or  tissue-forming  compounds  than  that  of  the 
turnip.     It  consists  very  nearly  of — 

Starch,  sugar,  &c., 46 

Protein  compounds,  (albumen,  &c.)        ,        .  30  to  35 
Oil  or  fat,      .        .        .        .        .        .        .  3 

Cellular  fibre, 9 

Saline  or  mineral  matter,      .        .        .        .  12  to  18 

100 

The  value  of  the  cabbage  in  feeding — especially  for  milcb 

f  Qrmrtarly  Jowmalof  Agrituliurs  Six  January  1852,  pp.  22J-2^. 


HAY,  STRAW,  AND  LEAVES  OF  TREES.  301 

COWS — and  its  exhausting  efifect  upon  the  soil,  are  not  therefore 
to  be  wondered  at. 

2.  The  Cauliflower  is  still  more  nutritious  than  the  cabbage 
leaf.  It  contains  about  64  per  cent  of  protein  compounds.  In 
this  respect  it  approaches  nearer  to  animal  food  than  any  ve- 
getable we  grow,  of  which  the  composition  has  yet  been  ex- 
amined. , 

3.  The  Mushroom  comes  nearest  to  the  cauliflower  in  this 
respect.  It  contains  about  56  per  cent  of  protein  compounds  ; 
and  though  by  some  found  to  be  indigestible,  its  nutritive  qua- 
lities are  very  generally  admitted. 

4.  The  Turnip-top,  though  apt  to  scour  cattle  if  given  too 
freely,  is  generally  as  nutritive  as  the  bulb.  It  contains  as 
large  a  per-centage  both  of  protein  compounds  and  of  phos- 
phates, especially  when  young.  The  young  sprouts  which  tur- 
nips, left  in  the  field,  throw  out  in  spring,  resemble  cabbage 
very  much,  and  are  very  nutritious.  Hence  the  reason  why 
turnips  which  have  thrown  out  large  leaves  in  spring  are  gene- 
rally found  less  valuable  in  feeding. 

The  composition  of  the  turnip-top  indicates  the  cause  both  of 
its  great  value  as  a  manure  when  left  upon  the  land,  and  why 
it  forms  a  very  appropriate  food  for  the  milch  cow  and  the 
growing  calf. 

5.  Hay  and  Straw  are  distinguished  by  the  large  proportion 
of  cellular  or  woody  fibre,  in  an  indigestible  state,  which  they 
contain.  Good  hay,  however,  contains  also  from  6  to  9  per 
cent  of  protein  compounds,  and  clover  hay  even  as  much  as  12 
per  cent ;  so  that,  in  muscle-forming  matter,  hay  is  nearly  as 
rich  as  our  English  wheat.  The  straw  of  our  white-corn  plants 
contains  only  3  or  4  per  cent  of  these  compounds.  Pea  and 
bean  straw  are  more  nutritious — good  pea  straw  approaching 
in  this  respect  to  the  best  clover  hay. 

6.  The  Leaves  of  Trees  are  often  very  nutritious ;  and  did 
they  not  frequently  contain  substances  which  render  them  un- 
palatable or  unwholesome  when  eaten,  they  might  be  very  ex- 


8<tt  COMPOSITION  OF  FRUITS. 

tensively  employed  as  food  for  cattle.  The  dry  tea-leaf  con- 
tains about  25  per  cent  of  protein  compounds,  chiefly  albumen, 
and  would  prove  as  nutritious  in  this  respect  as  an  equal  weight 
of  beans  or  peas,  were  it  the  fashion  in  Europe  to  eat  it.  The 
tobacco  leaf  contains  about  23  per  cent.  The  elephant — the 
largest  of  existing  quadrupeds — lives  much  upon  leaves  in  its 
native  forests  ;  and  in  some  Alpine  countries,  the  annual  har- 
vest of  dried  leaves  forms  an  important  part  of  the  winter's 
provision  for  the  domesticated  cattle.*     (See  p.  316.) 

It  is  not  surprising,  therefore,  that  leaves  should  form  a  valu- 
able manure,  or  that  poor  land  should  be  permanently  improved 
by  planting  it  with  trees.     (P.  158.) 

SECTION   V. OF    THE    COMPOSITION    OF    FRUITS,     AND  THE   EFFECT 

OF   SOIL   UPON   THEIR   QUALITY  AND   FLAVOR. 

To  fruits  it  is  necessary  to  do  little  more  than  allude  in  the 
present  work.f  They  contain  from  70  to  90  per  cent  of  water 
— the  quantity  diminishing  as  the  fruit  ripens.  In  the  fleshy 
fruits — plums,  peaches,  &c. — when  ripe,  the  water  forms  about 
75  per  cent ;  in  apples,  pears,  and  gooseberries,  a  little  more 
than  80  per  cent  of  the  whole  weight.  The  dry  matter  con- 
tains chiefly  sugar  and  pectic  acid,  with  a  considerable  propor- 
tion of  protein  compounds  and  of  soluble  phosphates.  Fruits 
are  therefore  fitted  to  nourish  as  well  as  to  refresh.  The  dried 
gooseberry  contains  about  9  per  cent  of  protein  compounds. 
The  acidity  of  our  usually  cultivated  fruits  is  due  to  the  pre- 
sence of  variable  quantities  of  malic  and  citric  acids. 

In  cider,  perry,  and  wine  countries,  the  nutritive  qualities  of 

*  "  For  several  miles,  when  crossing  the  high  Alps  of  Savoy,  we  ob- 
Berved  the  peasants  stripping  the  mountain  ash  trees  of  all  their  leaves,  for 
their  cattle  during  the  winter." — Weld's  T&wr  in  Auvergne  and  Piedmont—' 
[Were  these  leaves  gathered  for  food  or  for  litter  ?] 

f  For  fuller  infoniation,  see  the  Author's  published  Lectures. 


INFLUENCE  OF  TIME  OF  CUTTING.  303 

the  apple,  pear,  and  grape  are  seen  in  the  use  of  the  refuse  of 
the  mills  in  feeding  pigs  or  other  animals ;  or  where  it  is  not 
used  up  in  this  way,  these  qualities  are  equally  shown  by  the 
profitable  employment  of  the  refuse  as  a  manure. 

Fruits  of  all  kinds,  like  our  corn  and  root  crops,  are  affected 
in  flavor  and  quality  by  the  soil  on  which  they  grow.  In  the 
Norman  orchard,  the  gout  de  terrain  is  a  recognised  quality 
both  in  the  apple  and  in  the  cider.  The  extended  apple  and 
peach  culture  of  North  America  has  led  to  similar  observations  ; 
and  the  peculiar  qualities  possessed  by  the  wines  of  neighboring 
vineyards  are  familiar  everywhere.  There  are  only  three  farms 
situated  on  the  side  of  a  hill  which  produce  the  famous  Con- 
stantia  wine.  The  same  grape  has  been  tried  in  various  parts 
of  the  Cape  colony  without  success.  Even  a  mile  from  the  hill 
the  wine  is  of  a  very  inferior  description.  In  Europe,  on  the 
banks  of  the  Rhine,  the  Johannisberg  is  equally  well  known  for 
the  unique  qualities  of  its  celebrated  wine. 

SECTION  VI.— INFLUENCE  OF  THE  TIME  OF  CUTTING  ON  THE  QUANTITY 
AND  QUALITY  OF  THE  PRODUCE  OF  HAY  AND  CORN. 

1.  Hay. — The  period  at  which  hay  is  cut,  or  corn  reaped, 
materially  affects  the  quantity  (by  weight)  and  the  quality  of 
the  produce.  It  is  commonly  known  that  when  radishes  are 
left  too  long  in  the  ground  they  become  hard  and  woody — that 
the  soft  turnipy  stem  of  the  young  cabbage  undergoes  a  similar 
change  as  the  plant  grows  old — and  that  the  artichoke  becomes 
tough  and  uneatable  if  left  too  long  uncut.  The  same  natural 
change  goes  on  in  the  grasses  which  are  cut  for  hay. 

In  the  blades  and  stems  of  the  young  grasses  there  is  much 
Bugar  and  starch,  which,  as  they  grow  up,  are  gradually 
changed  into  woody  or  cellular  fibre,  (p.  42.)  The  more  cons- 
pletely  the  latter  change  is  effected — that  is,  the  riper  the 
stem  of  the  plant  becomes — the  less  sugar  and  starch,  both 
readily  soluble  substances,  its  various  parts  contain.       And 


304  CCTTING  STRAW  AND  GRAIN. 

though  it  has  been  ascertained  that  cellular  fibre  is  not  wholly 
indigestible,  but  that  the  cow,  for  example,  can  appropriate  a 
portion  of  it  for  food  as  it  passes  through  her  stomach — yet  the 
reader  will  readily  imagine  that  those  parts  of  the  food  which 
dissolve  most  easily,  are  also  likely,  other  things  being  equal, 
to  be  most  nourishing  to  the  animal. 

It  is  ascertained,  also,  that  the  weight  of  the  hay  or  of  the 
straw  we  reap,  is  actually  less  when  it  is  allowed  to  become 
fully  ripe  ;  and  therefore,  by  cutting  soon  after  the  plant  has 
attained  its  greatest  height,  a  larger  quantity,  as  well  as  a  bet- 
ter quality  of  hay,  will  be  obtained,  while  the  land  also  will  be 
less  exhausted. 

2.  Straw. — The  same  remarks  apply  to  crops  of  corn — both 
to  the  etraw  and  to  the  grain  they  yield.  The  rawer  the  crop 
is  cut,  the  heavier  and  more  nourishing  the  straw.  Within 
three  weeks  of  being  fully  ripe,  the  straw  begins  to  diminish  in 
weight ;  and  the  longer  it  remains  uncut  after  that  time,  the 
lighter  it  becomes,  and  the  less  nourishing. 

3.  Grain. — On  the  other  hand,  the  ear,  which  is  sweet  and 
milky  a  month  before  it  is  ripe,  gradually  consolidates — the 
sugar  changing  into  starch,  and  the  milk  thickening  into  the 
gluten  and  albumen  of  the  flour.  As  soon  as  this  change  is 
nearly  completed,  or  about  a  fortnight  before  it  is  ripe,  the 
grain  of  wheat  contains  the  largest  proportion  of  starch  and 
gluten.  If  reaped  at  this  time,  the  bushel  will  weigh  most, 
and  will  yield  the  largest  quantity  of  fine  flour  and  the  least 
bran. 

At  this  period  the  grain  has  a  thin  skin,  and  hence  the  small 
quantity  of  bran.  But  if  the  crop  be  still  left  uncut,  the  next 
natural  step  in  the  ripening  process  is,  to  cover  the  grain  with 
a  better  protection — a  thicker  skin.  A  portion  of  the  starch  of 
the  grain  is  changed  into  woody  fibre — precisely  as  in  the 
ripening  of  hay,  of  the  soft  shoots  of  the  dog-rose,  and  of  the 
roots  of  the  common  radish.  By  this  change,  therefore,  the 
quantity  of  starch  is  lessened  and  the  weight  of  husk  increased  ; 


WHEN  OATS  SHOULD  BE  CUT.  305 

hence  the  diminished  yield  of  flour,  and  the  increased  produce 
of  bran. 

Theory  and  experience,  therefore,  indicate  about  a  fortnight 
before  it  is  fully  ripe  as  the  most  proper  time  for  cutting  wheat. 
The  skin  is  then  thinner  and  whiter,  the  grain  fuller,  the  bushel 
heavier,  the  yield  of  flour  greater,  its  color  fairer,  and  the 
quantity  of  bran  less ;  while,  at  the  same  time,  the  straw  is 
heavier,  and  contains  more  soluble  matter  than  when  it  is  left 
uncut  until  it  is  considered  to  be  fully  ripe. 

In  regard  to  oats,  it  is  said  that  the  superiority  of  Ayrshire 
oatmeal  is  partly  owing  to  the  grain  being  cut  rather  glazy, 
(that  is,  with  a  shade  of  green  upon  it,)  and  the  straw  is  con- 
fessedly less  nourishing  for  cattle  when  the  crop  is  allowed 
to  stand  till  it  is  dead  ripe.  Early  cut  oats,  also,  are  heavier 
per  bushel,  fairer  to  the  eye,  and  usually  sell  for  more  money. 
A  week  before  full  ripeness,  however,  is  the  utmost  that  is  re- 
commended in  the  case  of  oats,  the  distance  of  the  top  and 
bottom  grains  upon  the  stalk  preventing  the  whole  from  becom- 
ing so  uniformly  ripe  as  in  the  ear  of  wheat. 

Barley  cut  in  the  striped  state  is  also  thinner  in  the  skin, 
sprouts  quicker  and  more  vigorously,  and  is  therefore  preferred 
by  the  maltsters.  It  is  also  fairer  to  the  eye,  and  generally 
brings  a  higher  price  in  the  market. 

SECTION  VII. OF  THE  RELATIVE  QUANTITIES  OF  STARCH  AND  GLUTEN 

IN  OUR  USUALLY  CULTIVATED  "CROPS. 

In  addition  to  the  details  already  given  in  regard  to  the 
composition  of  the  several  kinds  of  grain  and  roots  usually  cul- 
tivated in  this  country,  it  may  be  useful  to  exhibit,  in  a  tabular 
form,  the  relative  proportions  of  starch  and  gluten  contained  in 
each.  The  following  numbers  cannot  be  considered  as  precisely 
accurate,  yet  they  represent  pretty  nearly  the  average  quanti- 
ties of  these  two  substances  contained  in  100  lb.  of  our  common 


8VI  PROPORTIONS  OF  STARCH,  GLUTEN, 

crops  in  the  state  of  dryness,  &c.,  in  which  they  are  usually 
sent  to  market : — 

starch,  gum,  Gluten,  albu- 

and  sugar.  men,  &c. 

Wheat,  (flour,)         ....  55  10  to  19 

Bran  of  whea^         ....  —  16 

Barley, 60  12  to  15 

Oats,  (without  husk,)        ...  60  14  to  19 

Eye, 60  10  to  15 

Indian  com  (maize,)         ...  TO  12 

Bran  of  do —  13 

Rice, 75  7 

Beans,  peas,  vetches,  and  lentils,      .  40  to  50  24  to  28 

Linseed, 40  24 

Potatoes,         .....  18  2        • 

Do.       sliced  and  dried,        .        .  72  8 

Turnips,  carrots,  and  mangold- wurtzel,  9  to  11  IJ  to    2 

Do.        sliced  and  dried,      ,         .  90  12  to  16 

Cabbage,          .        .        .        ,        .  —  30  to  35 

These  numbers  are  somewhat  open  to  correction.  Indeed,  if 
the  reader  recollects  what  has  been  stated  in  the  previous  sec- 
tions, in  regard  to  the  variable  quality  of  the  different  crops  we 
raise,  he  will  understand  that  the  numbers  contained  in  aU 
tables  such  as  this  are  to  be  regarded  only  as  approximations 
to  the  truth. 


SECTION    VIII. OF  THE   QUANTTTY  OF  OIL  OR  FAT  IN  GRAIN,   ROOT, 

AND  HAT  CROPS. 

It  is  generally  known  that  linseed,  rape-seed,  turnip-seed, 
hemp-seed,  poppy-seed,  and  the  seeds  of  many  other  plants, 
abound  so  much  in  oil,  that  it  can  be  squeezed  out  by  strong 
pressure,  as  is  done  in  the  mills  of  the  oil  manufacturers.  The 
kernels  of  some  nuts  also,  as  those  of  the  walnut,  the  hazel,  and 
the  beech,  contain  much  oil ;  and  even  some  trees,  as  certain 
species  of  the  palm,  yield  it  in  large  quantities. 

It  has  only  recently  been  discovered,  however,  that  all  our 
cultivated  grains  contain  an  appreciable  quantity  of  oil  or  fatty 


AND  OIL  IN  DIFFERENT  CRBPS. 


SOT 


matter — ^that  it  is  present  also  in  our  root  crops,  and  that  even 
in  straw  and  hay  it  exists  in  sensible  proportion. 

Soil,  climate,  mode  of  culture,  manure,  and  the  variety  of 
the  plant  we  grow,  all  affect  the  proportion  of  oil  which  its 
seeds,  stems,  or  roots  contain.  To  extract  this  oil  we  have 
only  to  reduce  the  part  of  the  plant  into  minute  fragments,  to 
boil  these  in  ether,  filter  the  solution,  and  afterwards  distil  off 
the  ether,  when  the  oil  or  fat  will  remain  behind.  It  is  usually 
more  or  less  of  a  yellow  color,  and  when  heated,  not  unfre- 
quently  emits  an  odor  peculiar  to  the  plant.  Thus  the  oil  from 
the  oat  emits,  when  heated,  the  well-known  odor  of  burned 
oatmeal. 

The  proportion  of  oil  contained  in  100  lb.  of  some  of  our 
more  commonly  cultivated  plants  is  as  follows  : — 


"Wheat  flour  (fine), 

Bran  of  wheac, 

Barley, 

Oats, 

Indian  corn. 

Linseed, 

Rape  and  turnip  seeds, 

Potatoes,  turnips,  and 

"Wheat  straw, 

Oat  straw, 

Meadow  hay, 

Clover  hay, 


2  to 

3  to 
2  to 
5  to 
5  to 


41b. 
5  1b. 
3  1b. 

8  1b. 

9  1b. 


30  to  35  lb. 
40  1b. 
1-5  lb. 

2  to  3i  lb. 

41b. 

2  to     5  lb. 

3  to     5  lb. 


The  quantity  of  fat  varies,  as  this  table  shows,  in  the  same 
kind  of  food.  These  variations  are  caused  by  differences  in 
the  soil,  manure,  climate,  season,  &c.  In  most  seeds,  however, 
the  largest  proportion  of  fat  resides  in  the  exterior  part,  near 
to  or  actually  in  the  husk  or  bran.  Hence  the  bran  of  wheat 
generally  contains  much  more  oily  matter  than  the  fine  flour. 
Thus  in  two  varieties  of  wheat,  the  fine  flour  from  which  con- 
tained only  1^,  the  bran  contained  from  3|  to  5  per  cent  of  fat. 

To  this  large  quantity  of  oil,  bran  owes  part  of  its  value  in 
feeding  pigs,  as  we  shall  see  more  clearly  when,  in  a  subsequent 
chapter,  we  come  to  consider  the  important  part  which  thia 


308 


FOOD  TIELDED  BY  AN  ACRE 


fatty  matter  performs  in  the  artificial  rearing  and  fattening  of 
stock. 


SECTION   IX, ON  THE  ABSOLUTE  QUANTITY  OP   FOOD  YIELDED  BY  AN 

ACKE  OP  LAND  UNDER  DIFFERENT  CROPS. 

The  quantity  of  food  capable  of  yielding  nourishment  to 
man,  which  can  be  obtained  from  an  acre  of  land  of  average 
quality,  depends  very  much  upon  the  kind  of  crop  we  raise. 

In  the  seeds  of  corn,  when  fully  ripe,  little  sugar  or  gum  is 
generally  present ;  and  it  is  chiefly  by  the  amount  of  starch 
and  gluten*  they  contain,  that  their  nutritive  power  is  to  be 
estimated.  In  bulbs,  such  as  the  turnip  and  potato,  sugar  and 
gum  are  almost  always  present  in  considerable  quantity  in  the 
state  in  which  these  roots  are  consumed,  and  this  is  especially 
the  case  with  the  turnip.  These  substances,  therefore,  must  be 
included  among  the  nutritive  ingredients  of  such  kinds  of 
food. 

If  we  suppose  an  acre  of  land  to  yield  the  following  quan- 
tities of  the  usually  cultivated  crops,  namely — 


Of  wheat, 

25  bushels 

,or    1,5001b. 

Of  barley, 

35       .. 

or    1,800  . . 

Of  oats, 

50       .. 

or    2,100.. 

Of  pease. 

25       .. 

or    1,600.. 

Of  beans, 

25       .. 

or    1,600.. 

Of  Indian  com, 

30       .. 

or    1,800  . . 

Of  potatoes, 

12     tons. 

or  27,000  . . 

Of  turnips, 

30       .. 

or  167,000  . . 

Of  wheat  straw, 

u  .. 

or    3,000  . . 

Of  meadow  hay, 

IJ     .. 

or    3,400  . . 

Of  clover  hay, 

'■  2       .. 

or    4,500  . . 

Of  cabbage. 

20       ., 

or  45,000  . . 

The  weight  of  dry  starch,  sugar,  and  gum — pf  gluten,  albumen, 
casein,  &c. — of  oil  or  fat — and  of  saline  matter,  reaped  in  each 

*  Including  under  gluten  the  albumen,  avenin,  legumin,  and  casein — all 
the  varieties  of  the  protein  compounds,  in  short,  which  are  contained  iP 
grain.    (See  page  47.) 


OF  DIFFERENT  CROPS.  309 

crop,  will  be  represented  very  nearly  by  the  following  num- 
bers : — 


Husk  or 

Starch, 

Gluten,  al- 

Oiler 

SalinA 

woody  fibre. 

sugar,  &c. 

bumen,  &c. 

fat. 

matter. 

Wheat, 

225 

825  lb. 

180  lb. 

45 

30 

Barley, 

270 

1080 

230 

50 

50 

Oats, 

420 

1050 

300 

100 

•?5 

Pease, 

130 

800 

380 

34 

48 

Beans, 

160 

640 

420 

40 

50 

Indian  com, 

100 

1260 

220 

130 

30 

Potatoes, 

1080 

4800 

540 

45 

240 

Turnips, 

1340 

6000 

1000 

200 

450 

Wheat  straw. 

1500 

900 

40 

80 

150 

Meadow  haj, 

1020 

1360 

240 

120 

220 

Clover  hay, 

1120 

1800 

420 

200 

400 

Cabbage, 

430 

2300 

1300 

130 

600 

1.  If  it  be  granted  that  the  quantities  above  stated  are  fair 
average  returns  of  the  different  kinds  of  produce  from  the  same 
quality  of  land — that  the  acre,  for  example,  which,  in  our  cli- 
mate, produces  25  bushels  of  Avheat,  or  30  of  Indian  corn,  will 
also  produce  50  bushels  of  oats,  or  12  tons  of  potatoes,  or  30 
of  turnips,  and  so  on  * — then  it  appears  that  the  land  which, 
by  cropping  with  wheat,  would  yield  a  given  weight  of  starch, 
gum,  and  sugar,  would,  when  cropped  with  barley  or  oats, 
yield  one-fourth  more  of  these  substances — with  ^potatoes  about 
four  times  as  much — and  with  turnips  eight  times  the  same 
quantity.  In  other  words,  the  piece  of  ground  which,  when 
sown  with  wheat,  will  maintain  one  man,  would  support  one 
and  a  quarter  if  sown  with  barley  or  oats,  four  with  potatoes, 
and  eight  with  turnips — in  so  far  as  the  nutritive  power  of  these 
crops  depends  upon  the  starch,  sugar,  and  gum  they  contain. 

*  These  are  not  by  any  means  to  be  regarded  as  universally  equivalent 
crops.  Even  in  our  country,  local  climate  modifies  very  much  the  relative 
quantities  of  the  same  crops  obtained  in  different  localities.  Thus,  in  the 
Bouthem  part  of  Wigtonshire,  30  tons  of  Swedes,  20  tons  of  mangold,  and 
20  tons  of  white  carrots  per  acre  are  equivalent  crops,  wliile  in  Berkshire 
it  is  as  easy  to  grow  30  tons  of  mangold  as  20  tons  of  Swedes  per  acre. 
Bee  Journal  of  the  Royal  Agricultural  Society,  vol.  xiii.  part  i. 


31  ".  RELATIVE  NUTRITIVE  VALUES 

2.  Again,  if  we  compare  the  relative  quantities  of  gluten, 
&c.,  in  the  several  crops,  we  see  that  wheat,  barley,  and  Indian 
corn  yield,  from  the  same  breadth  of  land,  nearly  equal  quan- 
tities of  this  kind  of  nourishment — oats  one-half  more,  peas  and 
beans  upwards  of  twice,  potatoes  upwards  of  thrice,  turnips 
upwards  of  four  times,  and  cabbage  six  times  as  much  as  wheat  or 
Indian  corn. 

On  whichever  of  these  two  substances,  then — the  starch  or 
the  gluten — we  consider  the  nutritive  property  of  the  above 
kinds  of  food  to  depend,  it  appears  that  the  turnip  is,  on  the 
whole,  the  most  nutritive  crop  we  can  raise.  It  is  by  no  means 
the  most  nutritive,  weight  for  weight ;  but  the  largeness  of  the 
crop — here  taken  at  30  tons — affords  us  from  the  same  field  a 
much  greater  weight  of  food  than  can  be  reaped  in  the  form 
of  any  of  the  other  crops  above  mentioned. 

If,  again,  we  look  to  the  gluten  alone,  none  of  our  crops  can 
compete  with  the  cabbage,  even  supposing  the  crop  not  to  ex- 
ceed 20  tons  an  acre. 

3.  Further,  the  oil  or  fat  they  contain  is  not  without  its 
value  in  relation  to  the  nutritive,  and  especially  to  the  fattening 
properties  of  the  different  crops.  In  this  respect  also  the  tur- 
nip would  appear  to  be  superior  to  most  of  the  other  usual 
forms  of  vegetable  produce.  Clover  hay  and  Indian  corn  can 
alone  be  compared  with  it. 

In  these  two  facts  the  practical  farmer  will  see  the  peculiar 
adaptation  of  the  turnip  husbandry  to  the  rearing  and  fatten- 
ing of  stock.  Could  the  turnip  be  rendered  an  agreeable 
article  of  general  human  consumption,  the  produce  of  the  land 
might  be  made  to  sustain  a  much  larger  population  than  under 
any  of  the  other  kinds  of  cropping  above  alluded  to.  At- 
tempts have  been  made  to  grind  them,  and  convert  them  into 
meal,  as  is  done  with  the  potato;  but  the  cost  of  manufactur- 
ing, and  the  disagreeable  taste  of  the  meal,  have  hitherto  stood 
in  the  way  of  a  successful  prosecution  of  this  branch  of  rural 
industry. 


OF  DIFFERENT  VEGETABLE  SUBSTANCES.  31 

The  relative  nourishing  powers  of  different  vegetable  suo- 
stances,  or  their  value  for  food,  is  supposed  by  some  to  depend 
entirely  upon  the  relative  proportions  of  gluten,  &c.,  they  con- 
tain. According  to  this  view,  the  pea  and  the  bean  are  much 
more  nourishing,  weight  for  weight,  than  wheat,  or  any  other 
grain,  since  100  lb.  of  beans  would  afford  as  much  gluten  to  an 
animal  as  230  lb.  of  wheaten  flour  or  Indian  corn,  or  as  130  lb. 
of  oats  or  200  lb.  of  rye ;  and,  in  like  manner,  an  acre  of  cab- 
bage would  support  both  more  people  and  more  stock  even 
than  an  acre  of  turnips.  This  opinion,  however,  is  not  alto- 
gether correct. 

But  we  shall  be  aL7e  to  form  a  better  judgment  in  regard  to 
the  relative  value  of  the  starch  and  gluten,  as  well  as  to  under- 
stand the  importance  of  the  saline  matter  of  the  food,  when  we 
come  in  a  succeeding  chapter  to  consider  the  several  purposes 
which  the  food  is  destined  to  serve  in  the  animal  economy — 
what  different  substances  the  animal  must  derive  from  its  food 
in  order  to  nourish  its  growing  body,  to  maintain  its  existing 
rendition  when  full  grown,  or  to  admit  of  a  healthy  increase  in 
is  bulk. 


CHAPTER  XXIII. 

Of  milk  and  its  products. — The  properties  and  composition  of  milk. — Influ- 
ence of  breed,  constitution,  food,  soU,  &c.,  on  its  quantity  and  quality. — 
Adulteration  of  milk. — Composition  of  cream. — Cliuming. — Quality, 
composition,  preservation,  and  coloring  of  butter. — Theory  of  tlie  action 
of  rennet. — Manufacture,  quality,  and  varieties  of  cheese. 

Op  the  indirect  products  of  agriculture,  milk,  butter  and 
cheese  are  among  the  most  important.  They  are  in  reality  ne- 
cessaries of  life  in  all  civilised  countries,  and  are  almost  the  sole 
productions  of  many  agricultural  districts.  The  various 
branches  of  dairy  husbandry  present  also  many  interesting  sub- 
jects of  inquiry,  on  which  modern  chemistry  throws  much 
light. 

SECTION  I. OF  THE  PROPERTIES  AND  COMPOSITION  OF  inLE. 

Milk  is  a  white  opaque  liquid,  possessed  of  a  slight  but  pecu- 
liar odor.  It  is  heavier  than  water,  usually  in  the  proportion 
of  103  to  100.  When  left  at^-est  for  a  number  of  hours  it  se- 
parates into  two  portions — the  cream,  which  rises  to  the  sur- 
face, and  the  thinner  creamless  milk  on  which  it  floats.  When 
the  whole  milk  or  the  cream  alone  is  agitated  in  a  churn,  the 
fatty  part  of  the  milk  separates  in  the  form  of  butter,  while 
the  milk  itself,  butter-milk,  becomes  slightly  sour. 

If  left  to  itself  for  several  days,  milk  sours  and  curdles;  and 
if  in  this  state  it  be  placed  upon  a  linen  cloth,  the  liquid  part, 
or  whey,  will  pass  through,  while  the  curd  or  cheesy  part  will 
remain  on  the  cloth.  The  same  effect  is  produced  more  rapidly 
by  adding  vinegar  to  the  milk,  lemon  juice,  muriatic  acid  (spirit 
of  salt),  or  rennet.    In  Holland  the  milk  is  sometimes  curdled 


COMPOSITION  OF  MILK.  318 

for  the  manufacture  of  cheese  by  the  addition  of  muriatic  acid; 
but  in  most  countries  rennet  is  employed  for  this  purpose.  It 
is  coagulated  also  by  alcohol  or  any  strong  spirit,  and  hence, 
probably,  the  practice  of  adding  a  quantity  of  whisky  or 
brandy  to  the  rennet — as  is  done  in  many  dairy  districts. 

When  exposed  to  the  air  for  a  length  of  time,  milks  begins 
to  putrefy  and  to  ferment.  It  becomes  disagreeable  to  the 
taste,  emits  an  oflfensive  smell,  and  ceases  to  be  a  wholesome 
article  of  food. 

The  milk  of  nearly  all  animals  contains  the  same  ingredients 
— cheesy  matter  or  casein,  butter,  milk-sugar,  and  saline  mat- 
ter, but  in  different  proportions.  The  best  known  varieties  of 
milk  consist  nearly  of 


Woman. 

Cow. 

Ass. 

Goat 

Ewe. 

Casein,  (or  curd,) 

1.5    - 

4.5     - 

1.8 

-      4.1    - 

4.5 

Butter, 

3.6    - 

3.1    - 

0.1 

•      3.3    - 

4.2 

Milk-sugar, 

6.5     - 

4.8     - 

6.1 

-       5.3     - 

5.0 

Saline  matter, 

0.5     - 

0.6     - 

0.3 

-       0.6     - 

0.7 

"Water, 

87.9    - 

SY.O     - 

91.7 

-    86.7    - 

85.6 

100  100  100  100  100 

The  milk  of  the  ass  appears  from  the  above  table  to  resem- 
ble woman's  milk,  in  containing  little  cheesy  matter  and  much 
sugar.  It  contains  also  much  less  butter  than  any  of  the  other 
varieties  above  mentioned,  and  hence,  probably,  its  peculiar 
fitness  for  invalids. 

SECTION  II. — INFLUENCE   OF   BREED,   CONSTITUTION,    FOOD^   SOIl., 
&C.,  ON  THE  QUANTITY  AND  QUALITY  OF  THE  MILK. 

Both  the  quantity  and  the  quality  of  the  milk  are  affected 
by  a  great  variety  of  circumstances.  Every  dairy  farmer 
knows  that  his  cows  give  more  milk  at  one  season  of  the  year 
than  at  another,  and  that  the  quality  of  the  milk  also — its 
richness  in  butter  or  in  cheese — depends,  among  other  condi- 
tions, upon  the  kind  of  food  with  \<rhich  his  oows  are  fed.  It 
14 


814  INFLUENCE  OF  CIRCUMSTANCES 

will  be  proper  to  advert  to  these  circumstances  a  little  io 
detail. 

1.  The  quantUy  and  quality  of  the  milk  are  affected  by  the 
breed. — Small  breeds  generally  give  less  milk,  but  of  a  richer 
quality.  Good  ordinary  cows  in  this  country  yield  an  average 
produce  of  from  8  to  12  quarts  a-day.    Thus  the  dairy  cows  of 

Devonshire  give  12  quarts  a-day, 
Lancashire      -       8  to  9  quarts  a-day, 

Cheshire  and  )       „ .„  „  ■, 

Ayrshire,       [       «  quarts  a  day, 

during  ten  months  of  the  year ;  but  crossed  breeds  are,  in 
many  districts,  found  more  productive  of  milk  than  the  pure 
stock  of  any  of  the  native  races. 

The  influence  of  breed  both  on  the  quantity  and  on  the  qua- 
lity of  the  milk  appears  from  the  following  comparative  pro- 
duce of  milk  and  butter  of  one  cow  of  each  of  four  different 
breeds,  in  the  height  of  the  season,  and  when  fed  on  the  same 
pasture.    The 

Milk.  Butter. 

Edldemess  gave  29  quarts  and  38i  oz. 

Alderney,        -     19       . .  25    oz. 

Devon,             -     17       ..  28    oz. 

Ayrshire,        -    20       . .  34    oz. 

Not  only  was  the  quantity  of  milk  very  different  in  the  four 
cows,  but  the  produce  of  butter  also — the  Holderness,  in  the 
quantity  both  of  milk  and  of  butter,  being  greatly  superior  to 
all  the  other  breeds. 

The  milk  of  the  Holderness  and  of  the  Alderney  breeds 
was  equally  rich  in  butter,  as  was  the  case  also  with  that  of  the 
Devon  and  the  Ayrshire,  since  1  lb.  of  butter  was  yielded  by 

12  quarts  of  milk  from  the  Holderness  cow, 
2  . .  . .         Alderney  cow, 

9|  . .  . .        Devon  cow, 

9J  . .  . .        Ayrshire  cow. 

Som©  stocks  of  Jersey  cows  produce  1  lb.  of  butter  from  8J 


ON  THE  QUANTITY  AND  QUALITY  OF  MILK.         315 

quarts  of  new  milk,  the  year  round,  and  at  the  same  time  con- 
sume less  food  than  others. 

The  butter  of  the  milk  is  often  in  great  part  derived  directly 
from  the  fat  of  the  food.  Hence  the  value  of  food  which,  like 
Indian  corn  and  linseed  cake,  is  rich  in  oil.  Hence,  also,  those 
animals  which  lay  the  smallest  proportion  of  this  fat  upon  their 
own  bodies  will  be  likely  to  give  the  largest  proportion  in  their 
milk.  Thus  the  Ayrshires  and  Alderneys,  which  are  good 
milkers,  are  narrow  across  the  shoulders,  and  wiry  and  muscu- 
lar about  the  flanks.  They  give  a  rich  milk,  but  rarely  fatten 
well.  The  short-horns,  on  the  contrary,  are  celebrated  for  their 
fattening  tendency.  They  deposit  more  of  the  fat  under  their 
skin,  and  impart  less  of  it  to  their  milk.  In  both  breeds,  how- 
ever, there  are  striking  exceptions,  because — 

2.  The  individual  form  and  constitution  of  the,  cow  causes  both 
the  yield  and  the  richness  to  vary  much  among  animals  of  the 
same  breed.  Every  dairy  farmer  knows  that  some  Ayrshire, 
or  Holderness,  or  Devon  cows  are  better  milkers  than  others. 
And  even  when  they  yield  nearly  the  same  quantity  of  milk,  the 
richness  or  produce  in  butter  may  be  very  unlike.  Thus,  four 
cows  of  the  Ayrshire  breed,  fed  on  the  same  pasture,  gave  in 
the  same  week — the 

Milk.  Butter. 

First,        ...        84  quarts  which  yielded  3i  lb. 
Second  and  third,  each,     86  . .  . .        5^  " 

Fourth,     ...         88  ..  . .        7     " 

so  that  the  fourth,  though  it  produced  only  four  quarts  more 
milk,  gave  twice  as  much  butter  as  the  first. 

Individual  cases  of  extraordinary  productiveness  occur  now 
and  then.  Thus  a  Durham  cow  belonging  to  Mr.  Hewer  of 
Charleton,  Northampton,  gave  in  the  height  of  the  season  8 
imperial  gallons  of  milk  in  a  day,  yielding  3  lb.  of  butter.  A 
cow  upon  ordinary  keep  has  been  known  also  to  produce  as 
much  as  350  lb.  of  butter  in  a  year     The  tendency  to  yield 


818  CONSTITUTION  AND  FOOD. 

butter  is  no  doubt  constitutional,  like  the  tendency  to  lay  on 
fat. 

3,  The  kind  of  food  also  exercises,  as  all  cowfeeders  know, 
much  influence  upon  the  quantity  and  upon  the  richness  of  the 
milk.*  The  Swedish  turnip  and  the  cabbage  give  a  richer 
milk,  the  white  globe  turnip  a  larger  quantity,  while  both  vari- 
eties of  turnips  are  said  to  cause  a  greater  yield  of  milk  when 
tops  and  bulbs  are  given  together.  Culpepper  recommends  the 
leaves  of  the  black  alder  as  a  fodder  for  causing  cattle  to  give 
much  milli.  (See  p.  302.)  Spurry  is  said  to  have  a  similar 
effect.  When  fed  on  grass  and  brewers'  grains,  the  cow  yields 
a  larger  quantity  of  milk;  and  when  fed  on  malt  dust,  she 
drinks  much  and  milks  well. 

It  is  believed  also,  that  cabbage  and  the  leguminous  plants, 
such  as  clover,  tares,  &c. — as  well  as  the  cultivated  seeds  of 
such  plants,  beans,  peas,  &c. — promote  the  production  of 
cheese  ;  while  oilcake,  oats,  Indian  corn,  and  other  kinds  of 
food,  which  contain  much  oily  matter,  favor  the  yield  of  butter. 
The  cakes  left  by  oily  seeds,  linseed,  poppy  seed,  dodder,  sesa- 
min,  give  a  mUk  which  contains  more  solid  matter,  and  is  richer 
both  in  butter  and  cheese.  If  the  cake  be  not  old  or  rancid,  it 
does  not  impair  when  given  in  moderate  quantities,  but  rather 
increases  the  flavor  and  pleasantness  of  the  butter. 

If  the  food  contain  little  fat,  the  animal  still  produces  butter. 
It  has  the  power  of  changing  the  starch  and  sugar  of  its  food  into 
fat  during  the  process  of  digestion.  It  even  robs  its  own  body 
of  fat,  becomes  leaner,  and  thus  yields  more  fat  in  the  form  of 
butter  than  it  has  eaten  in  its  food.  Where  only  part  of  a 
dairy  of  cows  is  kept  for  their  butter,  and  the  rest  for  cheese, 
the  butter-milk  from  the  former  may  be  given  to  the  latter,  and 
thus  the  produce  of  cheese  increased.  In  the  State  of  New 
York,  cows  are  said  to  yield  100  lb.  more  cheese  in  a  year 

*  Hence  the  Ayrshire  adage,  "  The  cow  giies  the  milk  by  the  mon." 


INFLUENCE  OP  THE  SOII,.  311 

when  the  whey  from  their  own  milk  is  added  to  their  daily 
food. 

4.  Th&  nature  of  the  soil  also  in  which  plants  grow,  and  the 
manure  by  which  they  are  raised,  affects  their  influence  upon 
the  milk.  It  has  been  known  from  the  most  remote  times, 
that  when  fed  upon  one  pasture  the  cow  will  yield  more  butter, 
upon  another  more  cheese.  This  difference  must  depend  upon 
the  soil.  Again,  it  has  been  found  by  experiment,  that  vetches 
grown  upon  well-limed  or  marled  land  promote  the  production 
of  cheese,  while,  after  a  manuring  with  wood-ashes,  they  in- 
crease the  quantity  of  milk  and  of  cream,  (Sprengel.)  In 
Cheshire  the  addition  of  bones  has  greatly  increased  the  value 
of  the  grass,  and  the  produce  of  milk  and  cheese  ;  while,  as  to 
the  quality,  it  has  been  found  in  Leicester  that  the  manuring  of 
old  pasture  with  good  farm-yard  manure,  rendered  the  cheese 
for  three  years  nearly  unsaleable. 

On  this  curious  subject  numerous  experimental  researches  are 
still  required. 

5.  The  milk  is  affected  also  by  a  variety  of  other  circum- 
staiices.  Its  quantity  depends  very  much  upon  the  distance 
from  the  time  of  calving,  diminishing  as  the  calf  in  the  womb 
gets  older.  This  is  no  doubt  a  natural  adaptation  to  the  wants 
of  the  calf,  which,  in  a  state  of  nature,  gradually  ceases  to  re- 
quire support  from  its  mother.  A  cow  which,  during  the  first 
fifty  days  after  calving,  yields  24  quarts  of  milk  a-day,  may 
yield  no  more  than  6  quarts  a-day  after  six  months  have 
elapsed. 

The  quality  of  the  milk  is  better  from  cows  that  are  in  good 
condition  and  have  already  been  two  or  three  times  in  calf — it 
is  richer  in  warm  climates,  in  dry  seasons,  and  when  the  cow  is 
not  too  frequently  milked.  It  is  said  to  be  richer  when  cows 
are  kept  constantly  in  the  house  and  regularly  fed — those  which 
go  at  large  in  the  pasture  yielding  more  cheese.  When  a  cow 
is  allowed  to  go  dry  for  two  or  three  months  before  calving,  it 
is  believed  to  give  more  milk  the  following  season.     In  autumn 


818  ADULTERATION  OF  MILK. 

it  is  richer  upon  the  t*hole,  giving  a  less  proportion  of  butter 
bat  a  greater  of  cheese  (  Aiton,  )  while  it  becomes  poorer  in  both 
when  the  cow  is  in  calf.  The  first  milk  which  comes  from  the 
udder  is  also  poorer  than  that  which  is  last  drawn,  the  strip- 
pings  or  stroakings — and,  lastly,  the  quality  of  the  milk  is  very 
much  afiFected  by  the  treatment  and  moral  state  of  the  animal. 
Gentle  treatment  and  a  state  of  repose  are  favorable  to  the 
richness  of  the  milk  ;  while  anything  tliat  frets,  irritates  or  ha- 
rasses the  animal,  injures  its  quality.  I  need  scarcely  add  that 
«leanliness  and  good  ventilation  in  the  cow  and  milk  houses  are 
essential  to  the  good  flavor  of  milk. 

section   III. — OF   THE    ADULTERATION    OF   MILK. 

Milk  is  almost  everywhere  more  or  less  adulterated  with  wa- 
ter. In  Paris  and  the  neighborhood,  the  cream  is  taken  off, 
and  the  skimmed  milk  thickened  with  sugar  and  an  emulsion  of 
sweet  almonds  and  hemp-seed,  (Raspail.)  Skim  milk  may 
also  be  thickened  with  magnesia,  and  by  this  means  the  thick- 
ness of  cream  may  be  given  to  new  milk,  while  it  will  also  be 
kept  longer  sweet.  Common  soda  or  pearl  ash  is  sometimes 
added  to  milk  which  has  turned,  to  restore  its  sweet  taste. 

But  the  most  singular  adulteration  of  which  I  have  heard  is 
that  of  mixing  up  the  skim  milk  with  calf's  and  sheep's  brains. 
This  mixture  renders  it  thick  and  rich,  and  causes  a  coating, 
apparently  of  cream,  to  rise  to  the  surface,  which  it  requires  a 
nice- chemical  examination  to  distinguish  from  genuine  cream.* 

*  The  method  of  examination  is  to  treat  the  creamy  matter  with  ether, 
and  to  boil  what  the  ether  takes  up  with  water  containing  a  little  sulphuric 
acid.  If  the  cream  is  not  genuine,  the  acid  solution  will  then  give  with 
lime  or  baryta  trai33  of  phosphoric  acid. 


THE  CHURNING  OP  CREAM.  819 


SECTION   IV. — OF   THE  COMPOSITION  OF    CREAM    AND    THE    CHURNING 
OF   BUTTER. 

1.  Cream. — When  milk  is  left  at  rest  for  a  length  of  time, 
the  fatty  matter  which  floats  in  it  in  the  form  of  minute 
globules,  rises  to  the  surface  in  the  form  of  cream.  The  rapi- 
dity with  which  it  thus  rises  to  the  surface  depends  upon  the 
temperature  to  which  it  is  exposed — being  quicker  in  warm 
than  in  cold  weather.  Thus,  for  example,  when  milk  is  set 
aside  it  may  be  perfectly  creamed  in 

Hours.  Degrees,  F. 

36  when  the  temperature  of  the  air  is  50 
24  ..  ..  55 

18  to  20  . .  . .  63 

10  to  12  ..  ..  77 

while  at  the  temperature  of  34°  to  37°  F., — a  little  higher 
than  the  freezing  point  of  water, — milk  may  be  kept  for  three 
weeks  without  throwing  up  any  notable  quantity  of  cream. 

If  the  milk  when  new  is  placed  in  a  hot  basin,  and  covered 
over  with  another,  the  cream  is  thrown  up  more  quickly,  and  a 
larger  quantity  of  butter  is  obtained.  Of  course,  the  skimmed 
milk  will  be  so  much  the  poorer. 

The  cream  thus  thrown  up  contains  the  greater  part  of  the 
fatty  matter  of  the  milk,  mixed  with  a  small  proportion  of  the 
curd  and  much  water.  Cream  of  good  quality  in  this  country, 
when  skilfully  churned,  will  yield  about  one-fourth  of  its  weight 
of  butter;  or,  one  wine  gallon  of  cream  weighing  8 J  lb.  will 
give  nearly  2  lb.  of  butter. 

2.  Churning. — When  milk  or  cream  is  agitated  for  a  length 
of  time,  the  fatty  matter  gradually  separates  from  the  milk, 
and  collects  in  lumps  of  hutter.  There  are  several  circum- 
stauces  in  connection  with  the  churning  to  which  it  is  of  inte- 
rest to  attend. 

a.  In  the  churning  of  cream  it  is  usual  to  allow  the  cream  to 


TEMPERATURE  FOR  CREAM, 

stand  in  cool  weather  for  several  days,  until  it  becomes  dis 
tinctly  sour.  In  this  state  the  butter  comes  sooner,  and  more 
freely.  The  butter,  when  collected  in  lumps,  is  well  beat  and 
squeezed  from  the  milk.  In  some  places  it  is  usual  also  to 
wash  it  in  cold  water  as  long  as  it  renders  the  water  milky ;  in 
other  places  the  remaining  milk  is  separated  by  repeated 
squeezings,  and  by  drying  with  a  clean  cloth. 

b.  Clouted  cream  may  be  churned  with  advantage  in  the 
sweet  state — the  butter  separating  from  it  with  great  ease. 
Colonel  le  Couteur  states  that,  in  Jersey,  it  is  usual  to  make  ten 
pounds  of  butter  in  five  minutes  from  the  clouted  cream  of  the 
Jersey  or  Alderney  cow.  Clouted  cream  is  obtained  by  gra- 
dually heating  the  milk  in  deep  pans,  almost  to  boiling,  but  so 
as  never  to  break  the  skin  or  clout  that  forms  on  the  surface. 
The  cream  is  said  to  be  more  completely  separated  by  this  pro- 
cess than  by  any  other,  and  a  larger  quantity  of  butter  to  be 
obtained  from  the  milk. 

c.  The  whole  milk  may  also  be  churned,  after  being  allowed 
to  stand  till  it  has  attained  the  proper  degree  of  sourness,  which 
is  indicated  by  the  formation  of  a  stiff  brat  on  the  surface, 
which  has  become  uneven.  This  method  is  more  laborious,  re- 
quiring more  time  than  when  the  cream  only  is  used ;  but  it  has 
the  advantage,  as  many  practical  men  have  found,  of  yielding 
five  per  cent  more  butter  from  the  same  quantity  of  milk,  and 
of  a  quality  which  never  varies  in  winter  or  in  summer.  It  also 
requires  no  greater  precautions  or  more  trouble  to  be  taken  in 
warm  than  in  cold  weather. 

d.  Temperature. — This  latter  advantage  is  derived  from  the 
circumstance,  that  the  temperature  at  which  the  whole  milk 
ought  to  be  churned  is  higher  than  that  of  the  air  in  our  cli- 
mate, throughout  nearly  the  whole  course  of  the  year.  The 
temperature  at  which  milk  can  be  churned  most  economi- 
cally is  about  65°  F.,  a  degree  of  heat  which  the  air  seldom 
attains  in  our  warmest  summer  mornings.  The  dairy-maid  lias 
simply  to  add  hot  water  enough  to  the  milk  to  raise  it  to  65" 


TIME  REQUIRED  FOR  CHURNING.  321 

F.,  and  to  repeat  this  every  morning  of  the  year,  if  she  churns 
BO  often.  On  the  other  hand,  the  temperature  of  cream,  when 
churned,  should  not  be  higher  than  from  53°  to  55°  F.,  a  tem- 
perature beyond  which  the  air  often  rises.  It  becomes  neces- 
sary, therefore,  in  summer,  to  cool  the  milk-room  in  which  the 
cream  is  churned,  and,  by  churning  early  in  the  morning,  to  en- 
deavor to  keep  the  cream  down  to  the  proper  temperature. 

Thus,  in  churning  cream,  the  task  of  the  dairy-maid  is  a 
more  difficult  one.  In  winter,  she  must  add  hot  water  to  bring 
the  temperature  up  to  55°,  and  in  summer  must  apply  cold,  to 
keep  it  down.  In  this  she  sometimes  fails,  and  on  these  occa- 
sions the  quality  of  the  butter  suffers. 

e.  The  twie  required  for  churning  the  whole  milk  in  the  ordi- 
nary churn  is  from  three  to  four  hours,  while  the  cream  alone 
can  be  churned  in  about  an  hour  and  a  half.  A  churn,  how- 
ever, has  lately  been  introduced  which  churns  both  milk  and 
cream  in  a  much  shorter  period  of  time.  It  is  made  of  tin,  is 
of  a  barrel  shape,  and  is  placed  in  a  trough  of  water,  which  is 
heated  to  the  temperature  the  milk  or  cream  ought  to  be 
brought  to.  In  this  churn  the  butter  was  extracted  from 
cream,  at  the  temperature  of 

Kco  V   jr,  ri\  .v,;.,,,*^.,  (    Butter   was  harder,   but  no 

56°  i.  m  faO  minutes,     .    .    .  •{         u  ^4.     i.i      ^i     ^  n 

'  {  better  than  the  loUowing. 

58°  F.  in  10  to  20  minutes,      .      Butter  excellent. 

60«  F.  in  5  to  T  minutes,         .  \    ^^^  ,^*  ^f^    ^.^*   °^   S^"*^ 
'  [        color  and  quality. 

The  whole  milk  in  this  churn  gave  the  butter  in  one  hour  to 
one  hour  and  a  half.  Mr.  Burnett  of  Gadgirth  informs  me, 
that  he  obtains  in  this  churn  a  larger  quantity  of  butter  from 
the  cream  than  from  the  whole  milk.  Thus,  from  508  quarts 
of  milk — the  produce  of  five  cows  in  one  week  of  July  (1843) 
— ^he  obtained,  on  churning  the  whole  milk,  36  lb.  11  oz.  The 
cream,  on  the  other  hand,  yielded  by  an  equal  quantity  of  milk 
drawn  from  the  same  cows  during  another  week,  gave  him  37  lb. 
4  oz.,  being  a  difference  of  9  ounces,  or  about  3  per  cent  la 


B$/i  SMALL  BREEDS  GIVE  MOST  BUTTER. 

favor  of  the  cream,  which  is  contrary  to  general  experience 
with  the  ordinary  churn,  as  stated  in  the  previous  page. 

Other  persons  who  have  tried  tliis  churn  have  not  been  so 
successful  in  the  use  of  it  as  Mr.  Burnett.  Where  they  have 
obtained  the  butter  much  sooner  than  usual,  they  have  found 
reason  to  complain  of  its  quality.  Perhaps  in  these  cases  the 
churn  has  not  been  skilfully  used,  or  something  may  depend 
upon  the  quality  of  the  milk — since  the  cream  from  the  milk  of 
some  cows  is  said  in  the  ordinary  churn  always  to  come  to  but- 
ter in  ten  minutes  or  less. 

The  air  churn — a  still  more  recent  invention — which  agitates 
the  milk,  by  forcing  a  current  of  air  through  it,  is  said  to  bring 
the  butter  in  the  still  shorter  period  of  four  minutes. 

/.  The  largest  quantity  of  butter  from  a  given  weight  of  the 
same  food,  and  the  richest  milk,  is  yielded  by  the  milk  of  the 
smaller  races.  The  small  Alderney,  or  Jersey,  West  Highland, 
and  Kerry  cows,  give  a  richer  milk  even  than  the  small  Ayr- 
shire. But  the  small  Shetlander  is  said  to  surpass  them  all. 
These  breeds  are  all  hardy,  and  will  pick  up  a  subsistence  from 
pastures  on  which  other  breeds  would  starve. 

The  quantity  of  butter  yielded  by  different  cows  in  the  same 
yard,  and  eating  the  same  food,  is  sometimes  very  different. 
Some  will  yield  only  3  or  4  lb.  a  week,  while  more  will  give 
8  or  9  lb.,  and  a  few  15  lb.  a-week.  As  a  rare  instance,  I  may 
mention  that  a  cow  has  been  known  in  Lancashire  to  yield  up- 
wards of  22  lb.  in  seven  days. 

SECTION   V. —  OF    THE    QUALITY,    COMPOSITION,    PRESERVATION,    AND 
COLORING    OF    BUTTER. 

1.  7%e  quality  of  butter  varies  with  numerous  circumstances. 
The  kind  of  natural  pasture,  or  of  artificial  food,  upon  which 
the  cow  is  fed,  the  season  of  the  year,  the  breed,  the  individual 
constitution  and  state  of  health  of  the  animal,  the  mode  of 


QUALITY  OF  BUTTER  VARIES.  323 

churning,  the  cleanliness  of  the  cow  and  milk  houses,  &c.,  all 
more  or  less  affect  the  quality  of  the  butter. 

But  from  the  same  cow,  fed  on  the  same  food,  and  in  the 
same  circumstances,  a  richer  butter,  and  of  a  finer  and  higher 
flavor,  will  be  obtained  by  churning  the  last  drawn  portions  of 
the  milk.  So  the  first  cream  that  rises  gives  the  finest  flavored 
butter, — while  any  cream  or  milk  will  give  a  butter  of  better 
quality  if  it  be  properly  soured  before  it  is  churned,  and  be 
then  churned  slowly  and  at  a  low  temperature. 

2.  The  composition  of  butter. — Butter,  as  it  is  usually  brought 
to  the  market,  contains  more  or  less  of  all  the  ingredients  of 
milk.  It  consists,  however,  essentially  of  the  fat  of  milk,  inti- 
mately mixed  with  about  one-eighth  of  its  weight  of  water, 
and  a  small  quantity  of  casein  or  curd,  of  saline  matter,  and  of 
the  sugar  of  milk.  The  quantity  of  casein  (cheesy  matter  or 
curd)  seldom  amounts  to  one  per  cent  of  the  whole  weight  of 
the  butter. 

If  the  butter  be  melted  in  hot  water  several  times,  shaken 
with  renewed  portions  of  water  as  long  as  they  become  milky, 
and  left  then  to  repose,  it  will  collect  on  the  surface  in  the 
form  of  a  fluid  yellow  oil,  which  will  concrete  or  harden  as  it 
cools.  If  when  cold  it  be  put  into  a  linen  bag,  and  be  sub- 
mitted to  strong  pressure  in  a  hydraulic  or  other  press,  at  the 
temperature  of  60°  F.,  a  slightly  yellow  transparent  oil  will 
flow  out,  and  a  soUd  white  fat  will  remain  behind  in  a  linen 
cloth.  The  solid  fat  is  known  by  the  name  of  margerine,  and 
is  identical  with  the  solid  fat  of  the  human  body,  with  that  of  the 
goose,  and  with  that  which  causes  the  thickness  of  olive  oil 
when  exposed  to  the  cold.  It  is  very  similar  also  to  the  solid 
fat  of  palm  oil.  The  liquid  or  butter  oil  is  a  peculiar  kind  of 
fat  not  hitherto  discovered  in  any  other  substance. 

The  proportion  of  these  two  kinds  of  fat  in  butter  varies  con- 
siderably, and  hence  the  different  degrees  of  hardness  which 
different  samples  of  butter  present.  The  solid  fat  is  said  to 
abound  more  in  winter,  the  liquid  fat  in  summer.     Winter  and 


JH|4  SOLID  AND  LIQUID  FATS  IN  BUTTER. 

summer  samples  of  butter  manufactured  in  the  Yosges  were 
found  to  contain  per  cent  respectively  of 


Summer. 

Winter. 

Solid  fat  or  margerine, 

40 

65 

Liquid  lat  or  butter  oil, 

60 

36 

100  100 

These  proportions,  however,  will  be  found  to  vary  more  or 
less  in  almost  every  sample  of  butter  we  examine. 

In  Jersey,  the  drainings  of  the  curd  in  rich-cheese  making 
give  a  butter  which  is  inferior  for  eating  with  bread,  but  very 
superior  for  pastry.  It  is  peculiarly  hard,  and  fitted  for  such 
use  in  hot  weather.  It  probably  contains  more  of  the  solid  fat 
of  butter. 

3.  The,  preservation  of  butter. — Fresh  butter  cannot  be  kept 
for  any  length  of  time  in  our  climate  without  becoming  rancid. 
The  fats  themselves  undergo  a  change  ;  and  the  same  is  the 
case  with  the  small  quantity  of  milk  sugar  which  the  butter 
contains.  The  main  cause  of  this  change  is  the  casein  or  curd 
which  is  usually  left  in  the  butter.  The  proportion  of  this 
cheesy  matter  I  have  found  in  two  samples  of  fresh  butter  to 
vary  from  one-half  to  three-fourths  of  a  per  cent, — or  from  half 
a  pound  to  three-quarters  of  a  pound  in  100  pounds  of  butter; 
and  yet  this  small  quantity  is  sufficient,  if  the  butter  be  expos- 
ed to  the  air,  to  induce  those  chemical  decompositions  to  which 
the  disagreeable  smell  and  taste  of  rancid  butter  are  owing. 
The  butter  made  in  the  pure  air  of  the  Alpine  valleys  of  Pied- 
mont and  Switzerland,  after  a  complete  expression  of  the  milk, 
is  said  to  be  "  preserved  sweet,  or  at  least  fit  for  use,  through 
the  whole  season,  without  any  admixture  of  salt."  By  melting 
and  skimming  the  butter  also,  and  then  pouring  it  hot  into  u 
jar,  it  is  in  Switzerland  preserved  without  salt.  In  this  latter 
state  it  is  called  boiled  butter,  {buerre  cuit,)  and  is  chiefly  used 
for  cookery.* 

♦  Physician's  Holiday ,  hy  Dr.  Forbes,  p.  336. 


HOW  BUTTER  BECOMES  KANCIB.  325 

I  do  not  enter  here  into  the  theory  of  the  action  of  this 
casein,  nor  into  an  explanation  of  the  nature  of  the  chemical 
changes  themselves.*  It  is  sufficient  to  state,  that  this  evil 
action  of  the  cheesy  matter  may  be  entirely  prevented. 

a.  By  salting  immediately  after  the  butter  is  made,  and  be- 
fore the  cheesy  matter  has  had  time  to  become  altered  by  ex- 
posure to  the  air. 

l.  By  taking  care  that  any  water  which  may  remain  in  or 
around  the  butter  be  always  kept  perfectly  saturated  with  salt. 

c.  By  carefully  excluding  the  air  from  the  casks  or  other  ves» 
sels  in  which  the  butter  is  packed. 

So  long  as  the  cheesy  matter  is  kept  from  the  air,  and  in  a 
saturated  solution  of  salt,  it  will  neither  undergo  any  rapid 
alteration  itself,  nor  will  it  soon  induce  any  offensive  alteration 
in  the  butter. 

About  half  a  pound  of  salt  is  used  to  12  or  14  lb.  of  butter  ; 
but  when  salted  for  exportation,  or  for  the  use  of  the  navy,  one 
pound  of  salt  is  added  to  10  or  12  of  butter.  Though  many 
wash  their  butter,  it  is  a  rule  with  others  never  to  wash  it  or  dip 
it  into  water  when  intended  to  he  salted,  but  to  work  it  with  cool 
hands  till  the  butter  milk  is  thoroughly  squeezed  out,  and  then 
to  proceed  with  the  salting.  Theoretically,  I  should  consider 
this  latter  the  better  plan,  since  it  exposes  the  cheesy  matter 
less  to  the  air,  and  consequently  to  less  risk  of  incipient  decom- 
position. 

Some  fancy  they  cure  their  butter  better  by  dissolving  the 
salt  in  the  cream  before  churning,  while  many  consider  its  pre- 
servation and  good  quality  to  depend  much  upon  the  quality  of 
the  salt  that  is  employed. 

Some  prefer,  instead  of  salt  alone,  to  make  use  of  a  mixture 
of  one  part  of  sugar,  one  of  nitre,  and  two  of  salt  ;  and  some 
who  use  an  impure  salt,  consider  the  butter  to  be  improved  by 
washing  it  in  a  saturated  solution  of  salt. 

*  The  reader  will  find  these  fully  explained  in  the  Author's  published 
LKtiwrea  on  Agricultural  Chemistry  end  Geology,  2d  edit,  p.  976. 


t26  SOmtlNO  OF  MILE. 

It  is  said  that  rancid  butter  maybe  rendered  sweet  by  churn- 
ing it  with  fresh  sweet  milk,  in  the  proportion  of  six  pounds  of 
butter  to  the  gallon, 

4.  Coloring  hutter. — Butter  is  sometimes  colored,  and  the 
juice  of  scraped  carrots  is  not  unfrequently  employed  for  the 
purpose, 

SECTION    VI. OF  THE   SOURING    OF   MILK,    OF   MILK-SUGAR,    AND   OF 

THE  ACID  OF  MILK, 

1,  When  milk  is  left  to  itself  for  a  sufficient  length  of  time, 
It  becomes  sour  and  curdles.  This  takes  place  sooner  in  warm 
weather,  and  in  vessels  which  have  not  been  cleaned  with  suffi- 
cient care. 

Why  does  milk  thus  become  sour  1 

a.  Sugar  of  Milk. — I  have  already  stated  that  milk  contains 
a  quantity  of  a  peculiar  kind  of  sugar,  found  only  in  milk,  to 
which,  therefore,  the  name  of  milk-sugar  is  given.  It  differs 
from  common  cane  sugar  in  being  harder,  less  sweet,  and  much 
less  soluble  in  water.  Of  this  sugar,  milk  contains  generally  a 
larger  proportion  than  it  does  of  either  fat  or  curd,  (p.  313).  A 
gallon  of  milk,  therefore,  would  yield  a  greater  weight  of  sugar 
than  it  does  of  either  butter  or  cheese.  In  this  country,  the 
Bugar  is  usually  neglected.  In  our  cheese  districts,  it  is  given 
to  the  pigs,  and  sometimes  to  the  cows  in  the  whey  with  which 
they  are  fed.  In  Switzerland  and  elsewhere,  it  is  extracted  as 
a  profitable  article  of  commerce. 

b.  Add  of  milk. — When  milk  becomes  sour,  a  peculiar  acid 
is  formed  in  it,  to  which,  from  its  having  been  first  observed  in 
milk,  the  name  of  lactic  acid,  or  acid  of  milk,  has  been  given. 
To  this  acid  the  sourness  of  milk  is  owing.  The  same  acid  is 
produced  when  crushed  wheat — as  in  the  manufacture  of  starch 
from  wheat — wheaten  flour,  oat-meal,  pease-meal,  &c.,  or  when 
cabbage  and  other  green  vegetables  are  mixed  with  water,  and 


BUGAR  AND  ACID  OF  MILK.  321 

allowed  to  become  sour.     It  exists  also  in  small  quantity  in  the 
acorn,  (p.  289.) 

c.  But  how  is  the  acid  produced  ? — As  the  acid  of  milk  in- 
creases in  quantity,  the  sugar  of  milk  diminishes.  The  acid, 
therefore,  is  formed  from  or  at  the  expense  of  the  sugar.  There 
is  no  fermentation,  and  therefore  no  loss  of  matter  :  the  sugar 
is  merely  transformed  into  the  acid,  and  by  a  process  the  out- 
line of  which  it  is  very  easy  to  understand.  Like  cane  sugar, 
grape  sugar,  and  gum,  (p.  43,)  both  may  be  represented  by, 
or  may  be  supposed  to  consist  of,  carbon  and  water,  and  in  the 
same  proportions.     Thus, — 

Carbon.  Water. 

Sugar  of  milk  consists  of  .  .6        and        6 

Acid  of  milk,  (lactic  acid,)  .  .        6        and        6 

The  same  particles  of  matter,  therefore,  which  compose  the 
sugar,  are  made  to  assume  a  new  arrangement,  and,  instead  of 
a  sweet  sugar,  to  form  a  sour  acid.  In  the  interior  of  the  milk, 
nature  takes  down  and  builds  up  its  materials  at  her  pleasure, 
— using  the  same  molecules  to  form  now  this  and  now  that  kind 
of  substance — as  the  child  plays  with  its  wooden  bricks,  erect- 
ing a  hut  or  a  temple  with  the  materials  of  a  ruined  palace  or 
a  fallen  bridge.  So  nature  seems  to  play  with  her  materials, — 
working  up  all,  wasting  none, — yet  so  skilful  in  all  her  opera- 
tions as  to  excite  our  wonder,  so  secret  as  not  unfrequently  to 
escape  our  observation,  and  so  quick  as  often  to  show  that  she 
has  been  working,  only  by  the  striking  effects  she  has  produced. 
To  the  simple  peasant  and  to  the  instructed  philosopher,  it  is 
equally  a  matter  of  wonder,  and  almost  equally  unintelligible, 
that  the  same  number  of  material  particles  arranged  in  one  way 
should  affect  the  organs  of  taste  with  the  sweetness  of  sugai^ 
in  another  with  the  sourness  of  lactic  acid. 


828  WONDERFUL  CHANGES  OF  FORM. 


SECTION  VII. — OP  THE  CURDLING  OF   MILK,  OF   CASEIN,    AND   OP  THK 
ACTION    OF   RENNET. 

As  milk  becomes  sour,  it  also  thickens  or  curdles.  If  it  be 
then  slightly  heated,  the  curd  runs  together  more  or  less,  and 
separates  from  the  whey.  If  the  whole  be  now  thrown  upon 
a  linen  cloth  and  gently  pressed,  the  clear  whey  will  run  through 
and  the  curd  will  remain  on  the  cloth.  This  curd,  when  salted, 
pressed,  and  dried,  forms  the  cheese  which  we  consume  so  ex- 
tensively as  an  article  of  food. 

In  consequence  of  what  chemical  change  does  this  separation 
of  the  curd  take  place  ? 

1.  It  is  to  be  borne  in  mind,  that  this  curdling  does  not  take 
place  naturally  till  the  milk  has. become  sour.  The  acid  of  the 
milk,  therefore — the  lactic  acid — has  some  connection  with  the 
separation  of  the  curd.  It  is,  in  fact,  the  cause  of  the  curd- 
ling. 

2.  But,  in  order  to  understand  how  this  is,  we  must  turn  for 
a  moment  to  the  properties  of  the  curd  itself.  Chemically  pure 
curd  or  casein  is  a  protein  compound,  which  contains  less  sul- 
phur than  albumen  does,  and  no  phosphorus,  (p.  46.) 

a.  When  the  curd  of  milk  is  separated  carefully  from  the 
whey,  it  may  be  washed  or  even  boiled  in  water,  without  being 
sensibly  lessened  in  quantity.  Pure  curd  is  nearly  insoluble  in 
pure  water. 

b.  But  if  a  little  soda  be  added  to  the  water  in  which  the 
curd  is  heated,  it  will  dissolve  and  disappear.  Pure  curd  is 
soluble  in  a  solution  of  soda. 

c.  If  to  the  solution  of  the  curd  in  soda  and  water  a  quanti- 
ty of  the  add  of  milk  be  added,  this  acid  will  combine  with  the 
whole  of  the  soda — will  take  it  from  the  curd,  which  will  thus 
be  again  separated  in  an  insoluble  state.  The  curd  is  insolubU 
in  watery  rendered  sour  by  the  acid  of  milk. 

These  fiacts  explain  very  clearly  the  curdling  of  milk.     As  it 


WHY  THE  CURD  SEPARATES.  32& 

comes  from  the  cow,  milk  contains  a  quantity  of  soda  not  com- 
bined with  any  acid,  by  which  soda  the  curd  is  believed  to  be 
held  in  solution.  As  the  milk  becomes  sour,  this  soda  combines 
with  the  lactic  acid  produced,  and  thus  the  curd  becoming  in- 
soluble separates  from  the  whey — or  the  milk  thickens  and 
curdles. 

JNTow,  the  effect  which  is  thus  produced  by  the  natural  for- 
mation of  lactic  acid  in  the  milk,  may  be  brought  about  by  the 
addition  of  any  other  acid  to  it — such  as  vinegar  or  spirit  of 
salt.  And,  in  fact,  vinegar  is  used  now,  in  some  countries,  and 
in  ancient  times  was  used  more  extensively,  for  curdling  milk  ; 
while  in  some  of  the  cheese  districts  of  Holland,  spirit  of  salt 
(muriatic  acid)  is  said  to  be  employed  for  the  same  purpose. 
Sulijhuric  acid  has  been  also  recommended,  but  has  been  found 
to  give  the  cheese  an  unpleasant  taste. 

3.  But  in  most  dairy  countries  rennet  is  the  substance  used 
for  the  curdling  of  milk.  What  is  rennet  ?  and  how  does  it 
act? 

a.  The  stomach  of  the  calf,  of  the  kid,  of  the  lamb,  of  the  young 
pig,  andevenofthe  hare,*  when  covered  with  salt,  or  steeped  for 
some  time  in  water  perfectly  saturated  with  salt  and  then  dried, 
forms  the  dried  maw-skin  or  bag  which  is  used  for  the  prepara- 
tion of  rennet.  If  the  dried  skin  of  nine  or  ten  months  old  be 
steeped  in  salt  and  water,  a  portion  of  its  substance  dissolves, 
and  imparts  to  the  water  the  property  of  coagulating  milk. 
The  water  thus  impregnated  forms  the  rennet  or  yirning  of  the 
dairy-maid.  In  some  districts  it  is  usual  to  steep  several  skins 
at  once,  and  to  bottle  the  solution  for  after  use — mixed  with 
more  or  less  brandy,  v/hisky,  or  other  spirit.  In  others,  a  por- 
tion of  the  dry  skin,  sufficient  to  make  the  quantity  of  rennet 
required,  is  cut  off  the  night  before,  and  steeped  in  water  till 
the  milk  is  ready  in  the  morning.    To  this  solution  many  dairy* 

*  Tbres  haxes'  stomachs  are  considered  equal  to  one  calf's. 


330  HOW  RENNET  ACTS. 

maids  add  a  quantity  of  strong  spirit  before  putting  it  into  the 
milk,  which  probably  increases  its  coagulating  power. 

b.  The  rennet  thus  prepared  coagulates  more  or  less  readily, 
according  to  its  strength.     On  what  prmciple  does  it  act  ? 

If  a  piece  of  the  fresh  membrane  of  the  calf  s  stomach  or 
intestine,"  or  even  if  a  piece  of  fresh  bladder,  be  exposed  to  the 
air  for  a  short  time,  and  be  then  immersed  into  a  solution  of 
milk-sugar,  it  gradually  causes  the  sugar  to  disappear,  and  to 
change  into  lactic  acid — the  acid  of  milk.  If  the  salted  and 
dried  membrane  be  employed  instead,  it  will  produce  the  same 
eflfect,  only  with  greater  rapidity. 

But,  by  long  exposure  to  the  air  in  drying  the  surface,  the 
salted  membrane  undergoes  such  a  change,  that  a  portion  of  it 
becomes  soluble  in  water,  yet  still  retains  or  acquires,  even  in  a 
higher  degree,  the  property  of  changing  milk-sugar  into  the 
acid  of  milk.  It  is  this  soluble  portion  which  exists  in  the 
liquid  rennet. 

Now,  the  same  effects  which  the  membrane  produces  upon 
the  sugar  of  milk  alone,  it  produces  also  upon  the  sugar  as  it  is 
contained  naturally  in  the  milk — in  other  words,  the  rennet, 
when  added  to  the  warm  milk,  changes  the  sugar  into  the  add  of 
milk.  This  it  effects  more  or  less  rapidly  according  to  circum- 
stances, and  hence  the  different  length  of  time  which  elapses  in 
different  dairies  before  the  milk  is  fully  thickened. 

c.  The  addition  of  rennet,  therefore,  is  only  a  more  rapid  way 
of  making  the  milk  sour,  or  of  converting  its  sugar  into  lactic 
acid.  The  acid  produced,  as  in  the  natural  souring  of  milk, 
combines  with  the  free  soda,  and  renders  the  cheesy  matter  in- 
soluble, which,  in  consequence,  separates  ; — in  other  words,  the 
milk  curdles.  The  milk,  it  is  true,  does  not  become  sensibly 
sour,  because  the  production  of  acid  in  a  great  measure  ceases 
as  soon  as  the  soda  of  the  milk  is  fully  saturated  with  the  acid  ; 
and  if  any  excess  of  acid  be  produced,  it  is  taken  up  and  ab- 
sorbed or  separated  in  and  by  the  curd,  so  as  to  leave  the  whey 
somparatively  sweet.     Even  the  rennet  that  is  added  is  carried 


MANUFACTURE  OP  CHEESE.  331 

oflP  by  the  curd,  which  is  thus  often  injured  in  quality  if  too 
much  rennet  have  been  added,  or  if  its  smell  or  taste  have  been 
unpleasant.  The  sugar  that  remains  in  the  whey  is  thus  ena- 
bled to  retain  its  sweetness — that  is,  to  remain  unchanged  into 
acid — longer  than  it  could  have  done  had  any  excess  of  rennet 
remained  in  it  after  the  separation  of  the  curd. 

The  chemical  change  produced  by  rennet  in  curdling  milk, 
therefore,  is  precisely  the  same  as  that  which  takes  place  when 
milk  sours  naturally.  In  both  cases  the  lactic  acid  which  is 
formed  causes  the  milk  to  curdle. 


SECTION     VIII. OF     THE     MANUFACTURE     AND     THE     QUALITY      OP 

1.  The  manufacture  of  cheese  is,  generally  speaking,  con- 
ducted in  the  same  manner  in  all  countries.  The  milk  is 
curdled  by  the  addition  of  rennet,  vinegar,  muriatic  acid 
(spirit  of  salt,)  lemon  juice,  tartaric  acid,  cream  of  tartar, 
salt  of  sorrel, — by  sour  milk  even,  as  in  some  parts  of  Switzer- 
land,* or  by  the  decoction  of  certain  plants  or  flowers,  as  of  those 
of  the  wild  thistle,  employed  for  the  ewe  cheeses  of  Tuscany. 

The  curd  is  then  more  or  less  carefully  separated  from  the 
whey,  tied  up  in  a  cloth,  and  exposed  to  gentle  pressure.  In 
general,  the  curd  at  this  stage  is  broken  small,  and  mixed  with 
a  due  proportion  of  salt  before  it  is  allowed  to  consolidate  and 
dry.  For  the  thin  cheeses  of  Gloucester  and  Somerset,  how- 
ever, this  mode  of  salting  is  not  adopted,  the  whole  of  the 
salt  that  is  necessary  being  afterwards  rubbed  in  and  made  to 
penetrate  through  the  exterior  of  the  cheese. 

After  it  is  removed  from  the  press,  the  cheese  is  rubbed  ove? 

*  It  is  stated  by  old  cheese-makers  in  Nottinghamshire,  that  churned 
milk  added  to  cheese  milk  in  the  usual  way,  very  much  improves  both  the 
quality  and  taste  of  th3  cheese,  and  prevents  it  from  rising  after  it  la 
Htbde. 


832  THE  QUALITY  OP  THE  CHEESE 

with  salt,  or  is  covered  with  a  layer  of  it — at  a  later  period  ia 
more  or  less  frequently  anointed  with  butter,  is  kept  for  a 
week  or  two  in  a  rather  warmish  place,  and  is  frequently 
turned.  There  are  minute  details  to  be  attended  to,  where 
cheese  of  good  quality  is  desired,  with  which  the  skilful  and 
experienced  dairy-maid  is  familiar,  but  upon  which  it  is  unne- 
cessary here  to  dwell, 

2.  Tht  quality  of  the  cheese  varies  with  a  great  variety  of 
circumstances,  partly  natural  and  unavoidable,  but  partly  also 
to  be  controlled  by  art. 

a.  Thus  there  are  natural  differences  in  the  milk,  arising 
from  the  kind  of  grass  or  other  food  on  which  the  cows  are 
fed,  which  necessarily  occasion  corresponding  differences  in  the 
quality  of  the  cheese  made  from  it.  The  milk  of  different 
animals  also  gives  cheese  of  unlike  qualities.  The  ewe-milk 
cheeses  of  our  own  country,  of  Italy,  and  of  France,  and  those 
of  goat's  milk  made  on  Mount  d'Or  and  elsewhere,  are  dis- 
tinguished by  qualities  not  possessed  by  cow's  milk  cheeses  pre- 
pared exactly  in  the  same  way.  The  milk  of  the  buffalo  like- 
wise gives  a  cheese  of  pecuHar  qualities,  arising,  as  in  the  cases 
of  the  ewe  and  the  goat,  from  some  natural  peculiarity  in  the 
composition  of  the  milk  itself. 

h.  But  every  dairy  farmer  knows  that,  from  the  same  milk, 
cheeses  of  very  different  flavors,  and  of  very  unlike  values  in 
the  market,  may  be  made — that  the  mode  of  management  has 
not  much  less  to  do  with  the  peculiar  quality  of  his  dairy  pro- 
duce than  the  breed  of  cattle  he  uses,  or  the  pasture  on  whicf: 
his  cows  are  fed.  Very  slight  circumstances,  indeed,  affect  th  j 
richness,  flavor,  and  other  valuable  properties  of  his  cheese. 

Thus  if  the  new  milk,  when  the  rennet  is  added,  be  warmer 
than  95°  F.,  the  curd  is  rendered  hard  and  tough  ;  if  colder,  it 
is  soft,  and  difficult  to  free  from  the  whey.  If  heated  on  the 
naked  fire,  as  is  often  done,  in  an  iron  pot,  the  milk  may,  by  a 
very  slight  inattention,  become  fire-fanged,  and  thus  impart  ae 
unpleasant  flavor  to  the  cheese.     If  the  curd  stand  long  uar 


13  AFFECTED  BY  MANY  CIRCUMSTANCES.  333 

broken  after  the  milk  is  fairly  coagulated,  it  becomes  hard  and 
tough.  If  the  rennet  have  an  unpleasant  flavor,  or  if  too  much 
be  added,  the  flavor  and  keeping  qualities  of  the  cheese  are 
affected.  If  acids  are  used  instead  of  rennet,  the  properties  ot 
the  cheese  are  altered.  It  is  less  rich  if  the  whey  be  hastily 
and  with  much  pressure  squeezed  out  of  the  curd  ;  or  if  the 
curd  be  minutely  broken  up  and  thoroughly  mixed  and  stirred 
up  with  the  whey,  or  washed  by  it,  as  is  the  custom  in  Norfolk 
— instead  of  being  cut  with  a  knife,  so  that  the  whey  may 
flow  slowly  and  gently  out  of  it,  as  is  done  in  Cheshire  or  Ayr- 
Bhire — or  instead  of  being  placed  unbroken  upon  the  cloth,  as 
in  making  Stilton  cheese,  so  that  the  whey  may  drain  and 
trickle  out  spontaneously,  and  may  carry  little  of  the  fatty  mat- 
ter along  with  it.  Some  of  the  Cheshire  dairy-maids  give  their 
cheese  a  tendency  to  green  mould,  by  setting  or  curdling  their 
milk  at  a  low  temperature  ;  and  the  inferiority  of  Dutch  cheese 
is  ascribed  by  some  to  the  custom  of  soiling  or  feeding  in  the 
house,  which  affects  the  flavor  of  the  cheese  without  injuring 
the  health  of  the  animal. 

c.  The  kind  of  salt  also  which  is  used,*  the  way  in  which  the 
cheese  is  salted,  the  size  of  the  cheese  itself,  and,  above  all,  the 
mode  in  which  it  is  cured,  have  very  much  influence  upon  its  after 
qualities.  Hence  a  fair  share  of  natural  ability,  as  well  as  long  ex- 
perience, are  necessary  in  the  superintendent  of  a  large  dairy 
establishment,  when  the  best  quality  of  cheese  which  the  milk 
can  yield  is  to  be  manufactured  nniformly,  and  at  every  season 
of  the  year. 

SECTION  IX. — OF  THE  VARIETIES  OF  CHEESE. 

The  varieties  of  cheese  which  are  manufactured  are  very 

*  The  kind  of  salt  preferred  in  the  dairy  districts  of  the  west  of  Scotland 
is  an  impure  variety  from  Saltcoats,  which  contains  a  notable  quantity  ol 
the  deUquescent  salts,  (cUorides  of  hme  and  magnesium.)  These  salts  seem 
CO  keep  the  skin  of  the  cheese  moist,  and  to  assist  its  axmin,^ 


884  VARIETIES  OF  CHEESE. 

numerous,  but  the  greater  proportion  of  these  varieties  owe 
their  peculiar  qualities  to  the  mode  of  management  whicli  is  fol 
lowed  in  the  districts  or  dairies  from  which  they  come.  Natura. 
varieties,  however,  arise  under  the  same  general  management, 
and  from  the  same  milk,  according  to  the  state  in  which  the 
milk  is  used.     Thus  we  have — 

a.  Cream  cheeses,  which  are  made  from  cream  alone,  put  into 
a  cheese-vat,  and  allowed  to  curdle  and  drain  of  its  own  accord, 
and  without  pressure  ;  or  as  in  Italy,  by  heating  the  cream, 
and  curdling  with  sour  whey  or  with  tartaric  acid.  These 
cheeses  are  too  rich  to  be  kept  for  any  length  of  time. 

h.  Cream,  and  milk  cheeses,  when  the  cream  of  the  previous 
night's  milking  is  mixed  with  the  new  milk  of  the  morning,  be- 
fore the  rennet  is  added.  Tlie  English  Stilton  cheeses  and  the 
small  soft  Brie  cheeses,  so  much  esteemed  in  France,  are  made 
in  this  way. 

c.  Whole  or  full  milk  cheeses,  which,  like  those  of  Gloucester, 
Wiltshire,  Cheshire,  Cheddar,  and  Dunlop,  are  made  from  the 
uncreamed  milk.  These  cheeses,  like  the  preceding,  however, 
will  be  more  or  less  rich  according  to  the  way  in  which  the 
curd  is  treated,  and  according  as  the  milk  is  curdled  while 
naturally  warm,  as  in  the  best  Ayrshire  dairies,  and  in  some 
parts  of  Holland — or  is  mixed,  as  in  Cheshire  and  in  some  Ayr- 
shire dairies,  with  the  milk  and  cream  of  the  previous  evening. 

The  large  60  to  120  lb.  cheeses  of  Cheshire  will  not  stand, 
will  break  and  fall  asunder,  if  all  the  cream  is  left  in  the  milk. 
About  one-tenth  of  the  cream,  therefore,  is  skimmed  off  and 
made  into  butter.  About  20  lb.  of  butter  a-week  are  thus 
made  in  a  cheese  dairy  of  100  cows. 

d.  Half-milk  cheeses,  such  as  the  single  Gloucester,  are  made 
from  the  new  milk  of  the  morning,  mixed  with  the  skimmed 
milk  of  the  evening  before. 

e.  Skimmed-milk  cheeses — which  may  either  be  made  from  the 
milk  once  skimmed,  like  the  Dutch  cheeses  of  Ley  den,  twiu 
skimmed,  like  those  of  Friesland  and  Groningen,  or  skimmed 


WHEY  ANT  riJTTEB-MII,R  CHEESES.  335 

for  Ihrtt  or  fmir  days  in  succession,  like  the  horny  cheeses  of 
Essex  and  Sussex,  which  often  require  the  axe  to  break  them, 
and  are  sometimes  used  for  certain  purjioses  in  the  arts.* 

/.    Whey  cheeses  made  from  the  curd  which  is  skimmed  ofif  th« 
whey  when  it  is  heated  over  the  fire.     This  is  by  no  means 
poor  kind  of  cheese ;  and  good  imitations  of  Stilton  are  said  to 
be  sometimes  made  by  mixture  of  this  curd  with  that  of  the 
whole  milk. 

g.  Butter-milk  cheeses,  made  by  simply  straining  the  butter- 
milk through  a  cloth,  and  then  either  gently  heating  the  butter- 
milk, which  causes  the  curd  to  separate,  or,  as  is  sometimes 
done,  by  the  addition  of  rennet.  This  kind  of  cheese  is  not 
unworthy  of  attention,  as  it  is  often  richer  than  that  made 
from  milk  only  once  skimmed.  Though  it  cannot,  of  course, 
have  the  richness,  it  is  said  to  possess  some  of  the  other  cha- 
racteristic qualities  of  good  Stilton  cheese. 

h.  Vegetable  cheeses  are  made  by  mixing  vegetable  substances 
with  the  curd.  The  green  Wiltshire  is  colored  by  a  decoction 
of  sage  leaves,  marigold,  and  parsley.  I  do  not  know  if  it  is 
to  this  practice,  or  to  one  of  actually  mixing  the  sage  leave? 
with  the  curd,  that  Gay  alludes  in  the  line — 

"  Marbled  with  sage,  the  hardening  cheese  she  pressed." 

The  Schabzieger  cheese  of  Switzerland  is  a  mixture  of  the  curd 
obtained  from  the  whey  of  skimmed  milk,  with  one-twentieth  ot 
its  weight  of  the  dried  leaves  of  the  mellilot  trefoil.f 

i.  The  Potato  cheeses  of  Saxony  and  Savoy  consist  of  dry 
boiled  potatoes  mixed  with  a  half  or  a  third  of  their  weight,  or 
with  any  other  proportion  of  the  fresh  curd,  or  simply  with  sour 
or  with  skimmed  milk.     The  mixture  is  allowed  to  undergo  a 

*  Suffolk  cheese,  which  is  locally  kuown  by  the  name  of  "  Suffolk 
Bank,"  is  so  hard  that  "  pigs  grunt  at  it,  dogs  bark  at  it,  but  neither  ot 
tliem  dare  bite  it." 

f  Zieger  is  the  curd  separated  from  whey  either  by  a  fresh  addition  of 
add  or  in  some  other  way. 


886  POtATO  CHEESE. 

species  of  slight  fermentation  before  it  is  made  up  into  shapes. 
Such  cheeses,  when  well  cured,  are  said  to  form  a  very  agree- 
able article  of  diet,  and  to  be  capable  of  being  kept  for  a  long 
period  of  time.* 

*  For  further  details  in  regard  to  milk  and  its  products,  the  reader  is  re- 
ferred to  the  Author's  Lectwrea  on  AgrieiMwraX  Chemistry  and  Oeohgy,  2d 
edi^HM,  pp.  928  to  1008. 


CHAPTER  XXIY. 

On  the  feeding  of  animals. — Main  visible  functions  of  the  living  animal — 
The  food  must  supply  the  wants  of  respiration. — Nature,  wants,  and  pur- 
poses of  this  function. — The  daily  waste  of  the  muscular  parts  and  tissues 
of  the  body. — Food  necessary  to  repair  it. — Saline  and  earthy  matters 
contained  in  its  several  parts,  and  daily  rejected  by  the  body. — "Waste  or 
increase  of  fat  supplied  by  the  food. — Special  waste  in  the  perspiration. 
— Forms  in  which  the  solid  matter  of  the  tissues  escapes  in  the  urine  of 
animals. — General  balance  of  food  and  excretions. — Band  of  food  re- 
quired, as  indicated  by  the  composition  of  the  blood. — ^Importance  of  a 
mixed  food. 

The  food  of  plants  we  hare  seen  to  consist  essentially  of  two 
kinds,  the  organic  and  the  iiwrganic,  both  of  which  are  equally 
ju^ecessary  to  the  living  vegetable — equally  indispensable  to  its 
healthy  growth.  A  glance  at  the  purposes  served  by  plants  in 
the  feeding  of  animals,  not  only  confirms  this  view,  but  throws 
also  additional  light  upon  the  kind  of  inorganic  food  which 
plants  must  be  able  to  procure,  in  order  that  they  may  be  fitted 
to  fulfil  their  assigned  purpose  in  the  economy  of  nature. 

SECnON  I. — ^MAIN  VISIBLE  FUNCTIONS  OF  LIVING  ANIMALS. 

Man,  and  all  domestic  animals,  may  be  supported,  may  even 
be  fattened,  upon  vegetable  food  alone.  Vegetables,  therefore, 
must  contain  all  the  substances  which  are  necessary  to  build  up 
the  several  parts  of  animal  bodies,  and  to  supply  the  waste  at- 
tendant upon  the  performance  of  the  necessary  functions  of  ani- 
mal life. 

AU  living  animals  perform  three  main  or  leading  functions 
necessary  to  the  continuance  of  healthy  life. 
15 


888  7TTNCTI0NS  OF  THE  LIVING  ANIUAL. 

1".  They  breathe,  alternately  inhaling  and  exhaling  air  by 
means  of  the  lungs. 

2°.  They  digest,  dissolving  the  food  in  the  stomach,  and  se 
lecting  from  it  the  materials  necessary  to  form  blood. 

3°.  They  excrete,  rejecting  in  the  solid  excretions  and  the 
urine,  or  giving  oflF  from  the  skin  and  the  lungs — 

a.  That  part  of  the  food  which  cannot  be  dissolved  and 
made  use  of  as  it  passes  through  the  alimentary  canal. 

b.  The  materials  derived  from  the  decomposed  tissues  or 
parts  of  the  body  which  are  undergoing  a  constant  waste. 

To  the  wants  of  an  animal  performing  these  visible  functions 
in  a  healthy  and  regular  manner,  the  food  must  be  adapted  in 
kind  and  quantity.  I  shall  briefly  illustrate  what  these  wants 
demand. 

To  the  numerous  minor  and  invisible  functions  performed 
within  the  several  parts  of  the  living  body,  it  is  unnecessary  to 
advert  in  detail.  I  may  have  occasion  incidentally  to  advert 
to  one  or  two  of  the  more  interesting  of  these  ;  but  as  h 
healthy  blood  contains  all  that  is  necessary  to  the  discharge  Oi 
these  functions,  it  would  only  complicate  our  present  inquiry  to 
consider  their  several  direct  relations  to  the  imdigested  food  a<j 
it  is  introduced  into  the  stomach. 

SKOnON  n.-THE  FOOD  MUST   SUPPLY  THE  WANTS  OF  BESPIRATION. — 
NATUKE,  WANTS,  AND  PURPOSES  OF  THIS  FUNCTION. 

While  an  animal  lives  it  breathes.  It  alternately  draws  in 
and  throws  out  atmospheric  air  by  means  of  its  lungs. 

1.  When  this  air  enters,  it  contains  about  two  gallons  of 
carbonic  acid  in  every  5000  ;  when  it  escapes  from  the  lungs  it 
contains  2  gallons  or  upwards  in  every  100.  The  proportion  is 
increased  from  50  to  100  times.  Much  carbonic  acid,  there- 
fore, is  given  off  from  the  lungs  of  animals  during  breathing. 
Id  other  words,  living  animals  are  continually  throwing  off  car- 


CARBON  GIVEN  OFF  BY  THE  LUNGS.  339 

bon  into  the  air,  since  carbonic  acid  contains  about  two-sevenths 
of  its  weight  of  solid  carbon,  (p.  20.) 

A  man  of  sedentary  habits,  or  whose  occupation  requires  lit- 
tle bodily  exertion,  may  throw  off  in  this  way  about  five  ounces 
of  carbon  in  twenty-four  hours — one  who  takes  moderate  exep 
cise,  about  8  ounces — and  one  who  has  to  undergo  violent  bodily 
exertion,  from  12  to  15  ounces.  In  our  climate  about  one-fifth 
more  is  given  off  in  summer  than  in  winter. 

If  we  take  the  mean  quantity  respired  at  8  ounces,  then,  to 
supply  this  carbon  alone,  a  man  must  eat  18  ounces  of  starch 
and  sugar  every  day.*  If  he  take  it  in  the  form  of  wheaten 
bread,  he  will  require  1|  lb.  of  bread  ;  if  in  the  form  of  pota- 
toes, about  1^  lb.  of  raw  potatoes  to  supply  the  carbon  which 
escapes  through  his  respiratory  organs  alone. 

When  the  habits  are  sedentary,  5  lb.  of  potatoes  may  be 
sufficient  ;  when  violent  and  continued  exercise  is  taken,  12  to 
15  lb.  may  be  too  little.  At  the  same  time,  it  must  be  observed 
that  when  the  supply  is  less,  either  the  quantity  of  carbon  gi- 
ven off  will  be  less  also,  or  the  deficiency  will  be  supplied  at 
the  expense  of  the  body  itself,  especially  its  fatty  part.  In 
either  case  the  strength  will  be  impaired,  and  increased  supplies 
of  nourishing  food  will  be  required  to  recruit  the  exhausted 
frame. 

Other  animals  give  off  from  their  lungs  quantities  of  carbon 
proportioned  to  their  weights.  A  cow  or  a  horse,  eight  or  ten 
times  the  weight  of  a  man,  will  give  off  4  to  5  lb.  of  carbon. 
The  quantity  of  food  required  to  supply  this  carbon  will  be  pto- 
portionably  greater. 

I  have  in  the  above  calculations  supposed  that  the  whole  of 
the  carbon  given  off  from  the  lungs  is  derived  from  the  starch, 
sugar,  or  gum  of  the  food.  This  view  is  the  simplest,  and  most 
easily  intellegible.  It  only  requires  us  to  suppose  that  in  the 
system  the  starch  is  separated  into  carbon  and  water,  of  which, 

*  Since  12  lb.  of  starch  contain  about  5  lb.  of  carbon,  (see  p.  43.) 


B4  0  THE  BODY  FED  BY  OXYGEN. 

as  we  have  seen,  (p.  43,)  it  may  be  represented  to  consist ;  and 
that  the  former  is  given  or  burned  off  from  the  lungs  in  the 
form  of  carbonic  acid.  Bui  many  physiologists  do  not  regard 
the  process  as  being  really  so  very  simple.  They  consider  that 
the  carbon  given  off  is  partly  derived  from  the  gluten  or  flesh 
of  the  food,  as  well  as  from  the  starch  or  fat — ^in  which  case 
the  quantity  of  starch  or  sugar  in  the  food,  as  I  have  calculated 
it,  need  not  be  so  large  ;  and  it  is  certain  that  where  animals 
live  on  food  which  contains  no  starch  or  sugar,  and  but  little 
fat,  the  gluten  or  fleshy  fibre  it  contains  must  yield  the  carbon 
which  is  given  off  by  the  lungs. 

2.  But  when  the  air  escapes  from  the  mouth  of  a  breathing 
animal,  it  contains  much  moisture  also.  It  enters  comparatively 
dry,  it  comes  out  so  moist  as  readily  to  deposit  dew  upon  any 
cold  surface,  or  to  form  a  white  mist  in  a  wintry  atmosphere. 
This  water  is  given  off  by  the  lungs,  along  with  the  carbonic 
acid,  and,  like  it,  is  derived  from  the  food,  solid  or  liquid,  which 
has  been  introduced  into  the  stomach.  It  may  either  be  part 
of  the  water  which  has  been  swallowed  as  such,  or  the  water 
which  may  be  supposed  to  exist  in  the  starch  and  sugar  of  the 
food.  Or  it  may  be  water  formed  by  the  union  of  the  hydro- 
gen of  the  other  kinds  of  food  with  the  oxygen  inhaled  by  the 
lungs.  It  is  probably  derived  in  part  from  each  of  these  soot- 
ces,  in  proportions  which  must  vary  with  many  circumstances. 

3.  But  the  lungs  actually  feed  the  body.  The  air  which  en- 
ters contains  more  oxygen  than  when  it  returns  again  from  the 
lungs.  The  oxygen  which  disappears  equals  in  bulk  very  near- 
ly that  of  the  carbonic  acid  which  is  evolved.  This  oxygen 
enters  the  lungs,  through  them  into  the  blood,  and  with  the 
blood  flows  on  and  circulates  through  the  body.  It  also  en- 
ters partly  into  the  composition  of  the  tissues,  so  that  it  is  a 
real  food,  and  is  as  necessary  to  the  consferuction  of  the  human 
body  as  the  other  forms  of  food  which  are  usually  introduced 
into  the  stomach.    The  weight  of  oxyger  taken  up  by  the 


DAILY  WASTE  OP  TISSUES.  341 

lungs  exceeds  considerably  that  of  all  the  dry  solid  food  which 
is  introduced  into  the  stomach  of  a  healthy  man.  (See  p.  38t.) 
4.  The  purposes  served  by  the  oxygen  thus  introduced  into 
the  system  are  very  difficult  and  complicated.  But  an  inciden- 
tal circijpistance,  which  accompanies  all  its  operations  in  the 
system,  is  the  evolution  of  heat.  From  the  time  the  solid  di- 
gestible food  enters  the  blood  till  it  escapes  from  the  lungs,  or 
in  the  other  excretions,  it  is  continually  uniting  with  oxygen 
into  new  forms  of  combination,  and  at  each  change  heat  is 
produced  or  given  off.  Thus  the  animal  heat  is  kept  up,  and 
thus  it  is,  in  a  certain  sense,  correct  to  say  that  oxygen  is  taken 
in  by  the  lungs  for  the  purpose  of  giving  warmth  to  the  body, 
— or,  more  poetically,  that  the  body  is  a  lamp  fed  with  oil  from 
the  stomach,  and  with  air  from  the  lungs,  which  burns  with  a 
slow  and  invisible  flame,  but  which  ever  does  burn  while  life 
lasts,  and  maintains  a  gentle  warmth  through  all  its  parts. 

SECTION    III. — THE    FOOD    MUST    REPAIR   THE   DAILY   WASTE    OP   THE 
MUSCULAR   PARTS    AND   TISSUES   OF  THE   BODY. 

From  every  part  of  the  growing  as  well  as  of  the  full-grown 
body,  a  portion  is  daily  abstracted  by  natural  processes,  and  re- 
jected either  through  the  lungs  and  skin,  or  in  the  solid  and 
fluid  excretions.  This  proportion  is  so  great  that  in  summer 
the  body  loses  one-fourteenth,  and  in  winter  one-twelfth  of  its 
weight  daily,  when  no  food  is  taken.  And  if  food  be  continu- 
ously withheld,  the  mean  duration  of  life  is  only  fourteen  days, 
and  the  weight  diminishes  two-fifths.  But  the  waste  or  change 
of  material  proceeds  more  rapidly  when  the  animal  is  well  fed, 
so  that  the  opinion  now  prevails  among  physiologists  that  every 
twenty  or  thirty  days  the  greater  part  of  the  matter  of  the  hu- 
man body,  when  adequately  fed,  is  constantly  renewed.  This 
waste  of  the  tissues  is  more  rapid  in  women  than  in  children,  in 
men  than  in  women,  and  most  of  all  in  men  between  the  ages 
of  30  and  40.    The  amount  of  waste  is  the  measure  of  life. 


342  COMPOSITION  OF  FIBRIN. 

The  materials  for  this  change  must  be  supplied  by  the  food 
And  the  quantities  required  must  be  adapted  to  the  nature, 
age,  and  sex  of  the  animal. 

The  muscles  of  animals,  of  which  lean  beef  and  mutton  are  ex- 
amples, are  generally  colored  by  blood  ;  but  when  washed  with 
water  for  a  length  of  time,  they  become  quite  white,  and,  with 
the  exception  of  a  little  fat,  are  found  to  consist  of  a  white  fibrous 
substance,  to  which  the  name  oi  fibrin  has  been  given  by  chem- 
ists. The  clot  of  the  blood  consists  chiefly  of  the  same  sub- 
stance ;  while  skin,  hair,  horn,  and  the  organic  part  of  the 
bones,  are  composed  of  varieties  of  gelatine.  This  latter  sub- 
stance is  familiarly  known  in  the  form  of  glue,  and  though  it 
differs  in  its  sensible  properties,  it  is  remarkably  similar  to  fibrin 
in  its  elementary  composition,  as  well  as  to  the  white  of  the 
egg,  {albumen,)  to  the  curd  of  milk,  (casein,)  and  to  the  gluten 
of  flour.  They  all  contain  nitrogen,  and  the  three  latter  con- 
sist of  the  four  organic  elementary  bodies  very  nearly  in  the 
following  proportions  : 

Carbon,  ......        65 

Hydrogen,        ......  7 

Nitrogen,  .  .  .  .  .  .16 

Oxygen,  with  a  little  sulphur  and  phosphorus,  .        22 

100 

Gelatine  or  dry  glue  contains  about  2  per  cent  more 
nitrogen. 

The  quantity  of  one  or  other  of  these  substances  removed 
from  the  body  in  24  hours,  either  in  the  perspiration,  (p.  369,) 
or  in  the  excretions,  amounts  to  about  five  ounces,  containing 
350  grains  of  nitrogen  ;  and  this  waste  at  least  must  be  made 
up  by  the  gluten,  fibrin,  or  other  protein  compounds  of  the 
food. 

In  the  1|  lb.  of  wheaten  bread,  supposed  in  the  previoua 
section  to  be  eaten  to  supply  the  carbon  given  off  by  the  lungs, 
there  will  be  contained  also  about  3  ounces  of  gluten — a  sub- 


FOOD  CONSUMED.  343 

stance  nearly  identical  with  fibrin,  and  capable  of  taking  its 
place  in  the  animal  body.  Let  the  other  two  ounces  which  are 
necessary  to  supply  the  daily  waste  of  muscle,  &c.,  be  made  up 
in  beef,  of  which  half  a  pound  contains  2  ounces  of  dry  fibrin, 
and  we  have — 

For  For  waster 

respiration.  of  muscle,  &c. 

1|  lb.  of  bread  yielding  18  oz.  starch  and  3  oz.  of  gluten. 
8    oz.  of  beef  yielding  . .  2  oz.  of  fibrin. 


Total  consumed  by  ^  ,    luten  or 

respiration  and  the   >    18  oz.  starch  and  5  oz.    •}     f5u_;„ 
ordinary  waste.        )  ' 

If,  again,  the  T|  lb.  of  potatoes  be  eaten,  then  in  these  are 
contained  about  2|  ounces  of  gluten  or  albumen,  so  that  there 
remain  2i  ounces  to  be  supplied  by  beef,  eggs,  milk,  or  cheese. 

The  reader,  therefore,  will  understand  why  a  diet,  which  will 
keep  up  the  human  strength,  is  easiest  compounded  of  a  mix- 
ture of  vegetable  and  animal  food.  It  is  not  merely  that  such 
a  mixture  is  more  agreeable  to  the  palate,  or  even  that  it  is  ab- 
solutely necessary — for,  as  already  observed,  the  strength  may 
be  fully  maintained  by  vegetable  food  alone ; — it  is  because, 
without  animal  food  in  one  form  or  another,  so  large  a  bulk  of 
the  more  common  varieties  of  vegetable  food  requires  to  be 
consumed  in  order  to  supply  the  requisite  quantity  of  nitrogen 
in  the  form  of  gluten,  albumen,  &c.  Of  ordinary  wheaten 
bread  alone,  about  3  lb.  daily  must  be  eaten  to  supply  the  ni- 
trogen,* and  there  would  then  be  a  considerable  waste  of  car- 
bon in  the  form  of  starch,  by  which  the  stomach  would  be  over- 
loaded, and  which,  not  being  worked  up  by  respiration,  would 
pass  off  in  the  excretions.     The  wants  of  the  body  would  bb 

*  The  dry  flour  being  supposed  to  contain  15  per  cent  of  dry  gluten, 
(a  large  proportion,)  on  which  supposition  all  the  above  calculations  are 
made. 


844  8ALINE  MATTER  OF  FLESH  AND  BLOOD. 

equally  supplied,  and  with  more  ease,  by  1|  lb.  of  bread,  and  4 
ounces  of  cheese. 

Oatmeal,  again,  contains  at  least  one-half  more  nitrogen 
than  the  wheaten  flour  of  our  climate  (p.  283,)  and  hence  21b, 
of  it  will  usually  go  as  far  in  supplying  this  portion  of  the  na- 
tural waste  as  3  lb,  of  wheaten  flour,  and  the  stomach  will  be 
less  oppressed.  This  fact  throws  much  light  on  the  use  and 
value  of  what  has  been  called  the  natural  food  of  Scotland. 

The  stomach  and  other  digestive  apparatus  of  our  domestic 
animals  are  of  larger  dimensions,  and  they  are  able,  therefore, 
to  contain  with  ease  as  much  vegetable  food,  of  almost  any 
wholesome  variety,  as  will  supply  them  with  the  quantity  of  ni- 
trogen they  may  require.  Yet  eVery  feeder  of  stock  knows 
that  the  addition  of  a  small  portion  of  oil-cake,  or  of  bean- 
meal,  substances  rich  in  nitrogen,  will  not  only  fatten  an  ani- 
mal more  speedily,  but  will  also  sa,ve  a  large  hulk  of  other 
kinds  of  food. 

SECTION   IV. — ^THE    FOOD    MUST    SUPPLY    THE    SALINE    AND     EARTHY 
MATTERS  CONTAINED  IN  AND  DAILY  REJECTED  BY  THE  BODY. 

The  full-grown  animal  daily  rejects  a  quantity  of  saline  and 
earthy  matter  withdrawn  from  its  wasting  tissues  ;  while  the 
growing  animal  appropriates  also  every  day  an  additional  por- 
tion in  the  formation  of  its  increasing  parts.  The  food  must 
yield  all  this,  or  the  functions  will  be  imperfectly  performed. 

1,  Thejksh,  the,  blood,  and  the.  other  fluids  of  the  body  con- 
tain much  saline  matter  of  various  kinds — sulphates,  muriates, 
phosphates,  and  other  saline  compounds  of  potash,  soda,  lime, 
and  magnesia.  The  dry  muscle  and  blood  of  the  ox  leave, 
when  burned,  about  4J  per  cent  of  saline  matter  or  ash.  The 
composition  of  this  saline  matter  is  represented  in  the  follow 
ing  table  of  Enderlin  : — 


MINERAL  MATTto 


S  IN  THE  BODY. 


345 


Phosphate  of  soda,  (tribasic,)  . 

Chloride  of  sodium,  (common  salt,) 

Chloride  of  potassium,  . 

Sulphate  of  soda. 

Phosphate  of  magnesia, 

Oxide,  with  a  little  phosphate  of  iron. 

Sulphate  of  lime,  gypsum,  and  loss. 


Blood. 
16.77 

3.85 
4.19 
8.28 
1.45 

100 


Flesh. 
45.10 

45.94 

trace. 


97.88 


All  these  saline  substances  have  their  special  functions  to 
perform  in  the  animal  economy,  and  of  each  of  them  an  unde- 
termined quantity  daily  escapes  from  the  body  in  the  perspira- 
tion, in  the  urine,  or  in  the  solid  excretions.  This  quantity, 
therefore,  must  be  daily  restored  by  the  food. 

2.  It  is  interesting  to  remark  how  the  mineral  matter  diflfers 
in  kind  in  the  different  parts  of  the  body.  Thus,  blood  con- 
tains much  soda  and  little  potash — the  former  in  the  serum, 
the  latter  in  the  globules — the  cartilages  much  soda  and  no 
potash,  and  the  muscles  much  potash  and  little  soda.  So 
phosphate  of  lime  is  the  earth  of  bones,  and  phosphate  of 
magnesia  the  earth  of  the  muscles.  So  also  the  presence  of  fluo- 
rine characterises  the  bones  and  teeth,  and  that  of  silica,  the 
horny  parts,  hair  and  feathers  of  animals — while  an  abundance 
of  iron  distinguishes  the  blood  and  the  hair. 

The  distinction  now  noticed  between  the  blood  and  the  mus- 
cle is  not  brought  clearly  out  by  the  analysis  above  given  of 
the  comparative  composition  of  the  saline  matter  of  each.  It 
is  seen  more  clearly  in  the  following  comparison  : — 


The  mineral  matter  or  ash 


Common  salt. 
Chloride  of  potassium, 
Potash, 


Phosphoric  acid, 
Oxide  fff  iron, 

15* 


of  ox  blood 

of  ox  fleih 

contains, 

contains, 

per  cent. 

per  cent. 

47  to  51 

— 

—       — 

10 

7  -    8 

36 

12  -  14 

_- 

3-7 

36 

7  -  10 

I 

346  MINERAL  MATTERS  «^  THE  BODIt, 

•n         i.u    xA^^A    +>iorof'»'6,   as  a  common  storehouse,  each 
From  the  blood,  theret     ,  +.        t  v 

^    li.  •      1  ,  „  v;«/-^of  selection,  the  rameral  matter  which 
part  obtains,  by  a  kiP'  ' 

T^  1,  f /s*-  heen  accurately  determined  by  experiment 

^,  saline  matter  must  necessarily  be  excreted  every 

^m  the  body  of  a  healthy  man,  or  in  what  proportions 

'different  inorganic  substances  are  present  in  what  is  ex- 
-creted  ;  but  it  is  satisfactorily  ascertained,  that  without  a  cer- 
tain sufficient  supply  of  all  of  them,  the  animal  will  languish 
and  decay,  even  though  carbon  and  nitrogen,  in  the  form  of 
starch  and  gluten,  be  abundantly  given  to  it.  It  is  a  wise  and 
beautiful  provision  of  nature,  therefore,  that  plants  are  so  or- 
ganised as  to  refuse  to  grow  in  a  soil  from  which  they  cannot 
readily  obtain  an  adequate  supply  of  soluble  inorganic  food, — 
since  that  saline  matter,  which  ministers  first  to  their  own 
wants,  is  afterwards  surrendered  by  them  to  the  animals  they 
are  destined  to  feed. 

Thus,  the  dead  earth  and  the  living  animal  are  but  parts  of 
the  same  system, — ^links  in  the  same  endless  chain  of  natural  ex- 
istences. The  plant  is  the  connecting  bond  by  which  they  are 
tied  together  on  the  one  hand, — the  decaying  animal  matter, 
which  returns  to  the  soil,  connects  them  on  the  other. 

3.  The  hones  of  the  animal  are  supplied  with  their  mineral 
matter  from  the  same  original  source, — the  vegetable  food  on 
which  they  live.  The  dried  bones  of  the  cow  contain  55  per 
cent  of  phosphate  of  lime  with  a  little  phosphate  of  magnesia, 
those  of  the  sheep  10,  of  the  horse  67,  of  the  calf  54,  and  of  the 
pig  52  lb.  of  these  phosphates  in  every  hundred  of  dry  bone. 
All  this  must  come  from  the  vegetable  food.  Of  this  bone- 
earth,  also,  a  portion — varying  in  quantity  with  the  health,  the 
food,  and  the  age  of  the  animal — is  every  day  rejected.  The 
food,  therefore,  must  contain  a  daily  supply,  or  that  which 
passes  off  will  be  taken  from  the  substance  of  the  living  bones, 
and  the  animal  will  become  feeble. 

The  importance  of  this  bone-earth  will  be  more  apparent  il 


THE  FOOD  SUPPLIES  THE  INCREASE.  347 

we  consider, — First,  that  in  animals  the  bones  form  not  only  a 
very  important  but  a  very  large  part  of  their  bodies. 
The  body  of  a  full-grown  man  contains  9  to  12  lb,  of  clean  dry 
bone,  yielding  from  6  to  8  lb.  of  bone-earth.  In  the  horse  and 
sheep  the  fresh  moist  bone  has  been  estimated  at  one-eighth  of 
the  live,^  or  in  the  sheep  to  one-fifth  of  the  dead  weight,  and 
to  one-third  of  the  weight  of  the  flesh.  Second,  that  in  a 
growing  sheep  the  increase  of  bone-earth  amounts  to  about  3 
per  cent  of  the  whole  increase  in  the  live  weight.  And — 
Third,  that  every  hundred  pounds  weight  of  live  weight  indi- 
cates 5  or  6  of  phosphate  of  lime. 

It  is  kindly  provided  by  nature,  therefore,  that  a  certain  pro- 
portion of  this  ingredient  of  bones  is  always  associated  with 
the  gluten  of  plants  in  its  various  forms, — ^with  the  fibrin  of 
animal  muscle  and  with  the  curd  of  milk.  Hence  man,  from 
his  mixed  food,  and  animals,  from  the  vegetables  on  which  they 
live,  are  enabled,  along  with  the  nitrogen  they  require,  to  ex- 
tract also  a  sufficiency  of  bone-earth  to  maintain  their  bodies 
in  a  healthy  condition. 

SECTION   V. — THE   FOOD  MUST  SUPPLY  THE   WASTE   OR   INCREASE    OF 
FAT  IN  ANIMALS. 

Every  one  knows  that  in  some  animals  there  is  much  more 
fat  than  in  others,  but  in  all  a  certain  portion  exists,  more  or 
less  intermingled  with  the  muscular  and  other  parts  of  the 
body.*  This  fat  is  subject  to  waste,  as  the  muscles  are,  and 
therefore  must  be  restored  by  the  food.  All  the  vegetable  sub- 
stances usually  cultivated  on  our  farms  contain,  as  we  have 
seen,  (p.  306,)  a  notable  quantity  of  fatty  matter,  which  seems 
to  be  intended  by  nature  to  replace  that  which  disappears  na- 
turally from  the  body. 

*  At  Port  Philip,  in  the  boiling-houses,  a  Merino  sheep  of  55  lb.  givei 
20  lb.  of  tallow,  and  of  all  weight  above  65  lb.  four-fifths  are  taUo^- 


848  WASTE  OF  THE  FAT. 

A  full-grown  animal,  in  which  the  fat  may  be  regarded  as  in 
a  stationary  condition,  requires  no  more  fat  in  its  food  than  is 
necessary  to  restore  the  natural  loss.  In  such  an  animal  the 
quantity  of  fatty  matter  found  in  the  excretions  is  sensibly 
equal  to  that  which  is  contained  in  the  food. 

But  to  a  growing  animal,  and  especially  to  one  which,  is  fat- 
tening,  the  supply  of  fatty  matter  in  the  food  must  be  greater 
than  to  one  in  which  no  increase  of  fat  takes  place.  It  is  in- 
deed held,  that,  in  the  absence  of  oil  in  the  food,  an  animal 
may  convert  a  portion  of  the  starch  of  its  food  into  fat, — may 
become  fat  while  living  upon  vegetable  food  in  which  no  large 
proportion  of  fatty  matter  is  known  to  exist.  And  it  can 
hardly  be  doubted,  I  think,  that  the  organs  of  the  living  ani- 
mal are  endowed  with  this  power  of  forming  in  a  case  of  emer^ 
gency — that  is,  when  it  does  not  exist  ready  formed  in  the 
food — as  much  fatty  matter  as  is  necessary  to  oil  the  machinery, 
so  to  speak,  of  its  body.  But  the  natural  source  of  the  fat  is 
the  oil  contained  in  the  food  it  eats,  and  an  animal,  if  inclined 
to  fatten  at  all,  will  always  do  so  most  readily  when  it  lives 
upon  food  in  which  oil  or  fat  abounds. 

It  does  not  however  follow,  because  fat  abounds  in  the  food, 
that  the  animal  should  become  fatter, — since  if  starch  be  defi- 
cient in  the  food,  the  fat  containing  no  nitrogen,  may  be  decom- 
posed and  worked  up  for  what  may  be  called  the  purposes  of 
respiration.  This  working  up  of  the  fat,  already  existing  in 
the  body,  is  one  cause  of  the  rapid  emaciation  and  falling  away 
of  fat  animals  when  the  usual  supply  of  food  is  lessened,  or  for  a 
time  altogether  withheld.  The  fat  is  indeed  considered  by 
some  as  nothing  more  than  a  store  laid  up  by  nature  in  a  time 
of  plenty  to  meet  the  wants  of  respiration  when  a  season 
of  scarcity  arrives, — that  a  fat  animal  is  like  a  steam-frigate 
heavily  laden  with  fuel,  which  it  burns  away  during  its  voyage 
for  the  purpose  of  keeping  up  the  steam. 

It  is  by  reference  to  this  supposed  purpose  of  the  fat  of  the 
body,  and  to  the  possibility  of  using  it  up  for  the  purposes  of 


PURPOSES  SERVED  BY  THE  FAT,  349 

respiration,  that  the  benefits  of  repose,  of  shelter,  of  moderate 
warmth,  of  the  absence  of  light,  and  even  of  a  state  of  torpor, 
in  conducing  to  the  more  speedy  fattening  of  cattle  and  sheep, 
are  explained.  Exercise  causes  more  frequent  respirations, 
and  hence  a  greater  waste  of  that  part  of  the  food  which  should 
be  laid  on  in  the  form  of  fat.  Cold  also  has  the  same  eifect, 
since  more  heat  must  be  produced  in  the  interior  of  the  animal 
— in  other  words,  more  frequent  respiration  must  take  place,  in 
order  to  make  up  for  the  greater  loss  of  heat  by  exposure  to 
the  external  air. 

Thus,  as  was  stated  at  the  commencement  of  the  present 
chapter,  a  study  of  the  nature  and  functions  of  the  food  of  ani- 
mals throws  additional  light  upon  the  nature  also  and  final  uses 
of  the  food  of  plants.  It  even  teaches  us  what  to  look  for  iu 
the  soil — what  a  fertile  soil  must  contain  that  it  may  grow  nou- 
rishing food — what  we  must  add  to  the  soil  when  chemical 
analysis  fails  to  detect  its  actual  presence,  or  when  the  food  it 
produces  is  unable  to  supply  all  that  the  animal  requires. 

SECTION  VI. SPECIAL  WASTE  IN  THE  PERSPIRATION  OF  ANIMALS, 

AND  IMPORTANCE  OF  THIS  FUNCTION. 

Animals  perspire  that  they  may  live,  and  this  function  is  as 
necessary  to  a  healthy  life  as  either  breathing  or  digestion. 
The  skin,  like  the  lungs,  gives  off  carbonic  acid  and  absorbs 
oxygen.  But  it  diSbrs  from  the  lungs  in  giving  oflf  a  much 
larger  bulk  of  the  former  gas  than  it  absorbs  of  the  latter. 
The  quantity  of  carbonic  acid  which  escapes  varies  with  cir- 
cumstances. It  is  sometimes  equal  to  a  thirtieth,  and  some- 
times amounts  only  to  a  ninetieth  part  of  that  which  is  thrown 
off  from  the  lungs.  But  exercise  and  hard  labor  increase  the 
evolution  of  carbon  from  the  skin,  as  it  does  from  the  lungs. 
In  motion,  the  human  body  gives  off  nearly  three  times  as 
much  as  when  it  is  at  rest;  while  from  a  horse,  when  put  to  the 


350  CARBONIC  ACID  AND  NITROGEN  FROM  THE  SKIN. 

trot,  the  carbonic  acid  of  the  skin  augments  as  much  as  an 
hundred  and  seventy  times.     (Gerlach.) 

Water  is  also  given  off  from  the  skin  as  from  the  lungs,  and 
every  one  knows  that  fat  exudes  from  its  pores  and  lubricates 
the  surface  of  the. body.  The  salt  taste  of  the  perspiration  is 
an  equally  familiar  proof  that  a  portion,  at  least,  of  the  saline 
matter  derived  from  the  waste  and  change  of  materials  in  the 
body  escapes  through  this  channel. 

Nitrogen  also  escapes  from  the  skin.  The  quantity  of  nitro- 
gen in  the  food  is  a  third  or  a  fourth  greater  than  that  contained 
in  the  solid  and  liquid  excretions.  (Barral.)  This  third  or 
fourth,  therefore,  is  supposed  to  be  given  off  by  the  organs  of 
perspiration,  the  lungs  and  the  skin.  A  cow  or  a  horse  is  reck- 
oned to  exhale  by  the  skin  and  lungs  about  400  grains  of  nitro- 
gen daily  ;  a  man,  perhaps,  100  ;  and  a  sheep  or  pig  80  grains. 

(BOUSSINGAULT.) 

The  functions  of  the  skin,  therefore,  are  very  important ;  and 
thus,  in  the  practical  feeding  of  animals,  a  healthy  and  clean 
condition  of  the  skin  must  contribute  not  only  to  healthy  growth, 
but  to  a  profitable  employment  of  vegetable  produce  in  rearing, 
maintaining,  and  fattening  them.* 

SECTION  VII. FORMS  IN  WHICH  THE  SOLID  MATTERS  OF  THE  TISSUES 

ESCAPE  IN  THE  URINE. 

The  lungs  throw  off,  in  the  form  of  gas  or  vapor,  a  large  pro- 
portion of  the  matters  which,  after  being  taken  into  the  stomach, 
have  already  served  their  purpose  in  the  body.  The  kidneys 
remove  the  greater  part  of  that  which  is  derived  from  the 
destruction  of-  the  tissues.    The  solid  excretions  in  man  amount 

♦Six  pigs  were  put  up  together  for  seven  weeks.  Three  were  curry- 
combed  and  cared  for — the  other  three  left  to  themselves;  the  former 
three  consumed  five  bushels  of  pease  less,  and  had  gained  2  stones  4  pounds 
more,  than  the  uncurried  three.  The  skins  of  pigs  fed  in  tlie  forest,  in  th» 
eeoson  of  the  acoma,  are  white  and  shining. 


SALTS  AXD  NITROGEN  IN  THE  URINE.  351 

only  to  a  fourteenth  or  an  eighteenth  of  the  whole  food  con« 
sumed. 

In  a  state  of  health,  the  saline  substances  of  the  food  escape 
for  the  most  part  in  the  urine.  The  mineral  matter  contained 
in  that  part  of  the  solid  excretions  which  has  undergone  diges- 
tion, consists  chiefly  of  earthy  salts  and  of  iron. 

In  man,  and  in  our  domestic  animals,  the  nitrogen  of  the 
food  and  tissues  is  alSo  separated  from  the  blood  by  the  kidneys, 
and  is  found  in  the  urine.  It  is  chiefly  in  the  form  of  a  sub- 
stance to  which  the  name  of  urea  is  given.  In  birds,  serpents, 
and  insects,  it  is  separated  in  the  form  of  uric  acid.  The  urine 
voided  by  a  healthy  man  in  24  hours,  averages  about  40  ounces, 
and  contains  about  150  grains  of  solid  matter,  which  has  served 
its  purpose  in  the  system.  Of  this  solid  matter,  about  210 
grains  consist  of  urea,  8  of  uric  acid,  and  110  of  mineral  or 
saline  matter.  The  urine  of  the  horse  is  richer  in  urea  than 
that  of  the  cow,  and  that  of  the  cow  than  the  urine  of  man. 
It  is  this  urea  which,  during  the  fermentation  or  ripening  of 
urine,  becomes  changed  into  ammonia. 

The  urea  and  uric  acid  discharged  daily  in  the  urine  of  a 
healthy  man,  contains  about  half  an  ounce  of  nitrogen — to  fur- 
nish which  requires  3  ounces  of  dry  gluten,  albumen,  or 
flesh.  If  so  large  a  proportion  of  that  which  is  most  valuable 
in  food,  and  which  has  been  derived  from  the  decay  of  the  tis- 
sues of  the  body,  is  contained  in  the  urine,  it  ought  to  be  an 
important  object  to  the  farmer  to  contrive  some  method  of  re- 
turning it  without  loss  to  the  soil,  that  it  may  aid  again  in  rais- 
ing new  vegetables  as  food  for  other  animals. 

SECTION    VIII. GENERAL    BALANCE    OP    FOOD    AND    EXCRETIONS    IN 

MAN, 

The  general  balance  of  the  food  taken  into  the  human  body 
and  of  the  excretions  of  various  kinds,  has  been  thus  represent" 
ed  by  M.  Barral : 


S52  BALANCE  OF  FOOD  AND  EXCRETIONS. 

Every  100  parts  taken  in,  consist  of- — 
Food,  solid  and  liquid,  containing  in  all  V  5  per  cent  of  water    .     liA 
Oxygen  taken  in  by  the  lungs, 25.6 

100 
And  are  given  off  as — 
Water  perspired  by  the  lungs  and  skin,        .        .        .        .  34.8 

Carbonic  acid,  do.  do., 30.2 

Evacuations,  solid  and  liquid, 34.5 

Other  losses, 0.5 

100 

In  general,  the  substances  perspired  are  to  the  evacuations 
as  2  to  1. 

Of  course,  in  an  estimate  of  this  kind,  it  is  impossible  accu- 
rately to  put  down  the  several  quantities  given  off  in  the  form 
of  hair,  nails,  surface  skin — both  of  the  outer  and  inner  parts 
of  the  body — &c.,  &c.,  all  of  which  are  constantly  shed  or 
cut,  and  as  constantly  renewed.  It  is  useful,  however,  in  show- 
ing generally  the  relation  which  the  oxygen  inspired  bears  to 
the  other  food  which  the  stomach  receives,  and  the  proportion 
of  the  work  of  excretion  performed  respectively  by  the  per- 
spiring organs,  and  by  the  organs  of  evacuation. 


BECTION   IX. KIND  OF    FOOD   REQUIRED   BY   ANIMALS  AS   INDICATED 

BY  THE  COMPOSITION  OF  THE  BLOOD. 

A  knowledge  of  the  kind  of  food  required  by  animals  may 
be  gathered,  as  we  have  seen,  from  the  composition  of  the 
several  parts  of  the  animal  body,  and  a  study  of  the  functions 
they  perform.  The  muscles  must  be  sustained  ;  therefore  glu- 
ten, albumen,  ifec. — often  popularly  called  muscular  matter, 
must  be  eaten.  The  fat  of  the  body  must  be  renewed,  and 
hence  fat  should  be  present  in  the  food.  And,  as  much  carbon 
escapes  from  the  lungs  and  skin,  it  seems  natural,  if  not  abso- 
lutely necessary,  that  starch  or  sugar  should  be  introduced  into 
the  stomach  with  the  view  of  supplying  it.    The  mineral  mat« 


WHAT  THE  BLOOD  TEACHES.  853 

ter  of  the  flesh,  blood,  and  bones,  must  in  like  manner  be  pro- 
vided. 

The  study  of  the  excretions  indicates,  besides,  the  quantity  of 
food  of  each  kind  which  ought  to  be  consumed.  The  quantity  of 
carbon  evolved  in  the  form  of  carbonic  acid,  of  nitrogen  in  the 
forms  of  urea  and  uric  acid,  and  of  saline  matters  in  the  urine 
and  solid  excretions  of  a  healthy  man,  afford  a  means  of  ap- 
proximating very  nearly  to  the  quantity  of  each  which  a  suffi- 
cient food  ought  to  contain  ;  but  the  excretions  do  not  alone 
tell  us  in  what  forms  the  carbon,  nitrogen,  and  saline  matters 
are  best  suited  to  the  wants  of  the  animal. 

An  examination  of  the  blood  gives  us  this  latter  information 
very  clearly.  The  blood  consists  essentially,  besides  the  water, 
of  albumen,  sugar,  fat,  and  saline  matter.  The  main  purpose  or 
object  of  the  process  of  digestion  is  to  form  blood  ;  for  out  of 
the  blood  are  drawn  the  materials  necessary  to  the  wants  of  the 
bones,  and  of  the  various  tissues  and  fluids  of  the  body. 
Those  forms  of  vegetable  or  animal  matter,  therefore,  must  be 
best  adapted  for  food,  which  most  resemble  the  ingredients  of 
the  blood  which  is  to  be  produced  from  them.  These  will  give 
the  digestive  organs  least  trouble,  or  will  be  most  easily 
digested.  Thus  we  arrive  again  at  the  conclusion  that  a 
healthy,  nourishing,  and  easily  digestible  food  ought  to  contain 
gluten  or  albumen,  sugar  or  starch — which,  in  the  stomach, 
readily  changes  into  sugar — fat  either  of  animal  or  vegetable 
origin,  and  saline  or  mineral  matters  of  various  kinds.  Of 
course,  if  the  stomach  of  the  animal  be  in  an  unhealthy  condi- 
tion, the  quality  of  the  food  may  require  to  be  adapted  to  its 
unnatural  condition  ;  but  this  does  not  affect  our  general  con- 
clusion. 

SECTION  X. — IMPORTANCE  OF  A  MIXED  FOOD. 

All  these  different  modes  of  examining  the  question,  there- 
fore, indicate  not  only  the  advantage  but  the  necessity  of  a 


354  IMPORTANCE  OP  A  MIXED  FOOD. 

mixed  food  to  the  healthy  sustenance  of  the  animal  body. 
Hence  the  value  of  any  vegetable  production,  considered  as 
the  sole  food  of  an  animal,  cannot  be  accurately  determined  by 
the  amount  it  may  contain  of  any  one  of  those  substances,  all 
of  which  together  are  necessary  to  build  up  the  growing  body 
of  the  young  animal,  and  to  repair  the  natural  waste  of  such 
as  have  attained  to  their  fullest  size. 

Hence  the  failure  of  the  attempts  that  have  been  made  to 
support  the  lives  of  animals  by  feeding  them  upon  pure  starch 
or  sugar  alone.  These  substances  would  supply  the  carbon 
perspired  by  the  lungs  and  the  skin  ;  but  all  the  natural  waste 
of  nitrogen,  of  saline  matter,  of  earthy  phosphates,  and  probably 
also  of  fat,  must  have  been  withdrawn  from  the  existing  solids 
and  fluids  of  their  living  bodies.  The  animals,  in  consequence, 
pined  away,  became  meagre,  and  sooner  or  later  died. 

So  some  have  expressed  surprise  that  animals  have  refused 
to  thrive — have  ultimately  died,  when  fed  upon  animal  jelly  or 
gelatine  alone,  nourishing  though  that  substance,  as  fart  of  thz 
food,  undoubtedly  is.  When  given  in  sufficient  quantity,  gela- 
tine might  indeed  supply  carbon  enough  for  respiration,  with  a 
great  waste  of  nitrogen,  but  it  is  deficient  in  the  saline  in- 
gredients which  a  naturally  nourishing  food  contains. 

Even  on  the  natural  mixture  of  starch  and  gluten  which  ex- 
ists in  fine  wheaten  bread,  dogs  have  been  unable  to  live  be- 
yond 60  days,  though  others  fed  on  household  bread,  contain- 
ing a  portion  of  the  bran — in  which  earthy  matter  more  largely 
resides — continued  to  thrive  long  after.  It  is  immaterial  whe- 
ther the  general  quantity  of  the  whole,  food  be  reduced  too  low, 
or  whether  one,  of  its  necessary  ingredients  only  be  too  much 
diminished  or  entirely  withdrawn.  In  either  case  the  effect 
will  be  the  same — the  animal  will  become  weak,  will  dwindle 
away,  and  will  sooner  or  later  die. 

The  skill  of  the  feeder  may  often  be  applied  with  important 
economical  effects  to  the  proper  selection  and  mixture  of  the 


VALUE  OF  OILY  FOOD  IIT  FATTENING.  355 

food  he  gives  his  animals  generally,  and  at  various  stages  of 
their  growth. 

It  has  been  found  by  experiment,  for  example,  that  food 
which,  when  given  alone,  does  not  fatten,  acquires  that  pro- 
perty in  a  high  degree  when  mixed  with  some  fatty  substance, 
and  that  those  which  are  the  richest  in  the  muscle-forming  in- 
gredients produce  a  comparatively  small  effect,  unless  they  con- 
tain also,  or  are  mixed  with,  a  considerable  proportion  of  fatty 
matter.  Hence  the  reason  why  a  stone  of  linseed  has  been 
found  by  some  to  go  as  far  as  two  stones  of  linseed  cake,  and 
why  the  Rutlandshire  farmers  find  a  sprinkling  of  linseed  oil 
upon  the  hay  to  be  a  cheap,  wholesome,  and  fattening  addition 
to  the  food  of  their  cattle  and  horses. 

A  Merino  sheep  of  55  lb,  contains  about  20  lb.  of  fat,  but 
four-fifths  of  any  subsequent  addition  consists  of  tallow,  (p. 
347  note  ;)  hence  we  may  infer  that  oily  food  should  be  profit- 
able in  fattening  sheep.  To  pigs  the  same  remark  applifes ; 
and,  in  practice,  fat  of  any  kind,  animal  or  vegetable,  is  found 
to  be  a  profitable  addition  to  the  food  of  these  animals  when 
they  are  to  be  fattened  off. 


CHAPTER  XXV. 

Feeding  of  animals  continued. — Kind  and  quantity  of  food  necessary  to 
maintain  a  healthy  man. — Prison  dietaries. — Food  required  by  other 
animals. — Practical  value  of  the  constituents  of  milk  in  feeding  the 
growing  calf. — Effect  of  long-continued  dairy  husbandry  upon  the  quality 
and  produce  of  the  soil. — On  the  growing  of  wool,  and  its  effect  upon 
the  soil. — Of  the  practical  and  theoretical  values  of  different  kinds  of 
food. — Relative  proportions  of  food  for  man  yielded  by  the  same  herbage 
in  the  forms  of  beef  and  milk. — Influence  of  circumstances  in  modifying 
the  practical  values  of  animal  and  vegetable  food. — Concluding  observa- 
tions. 

Practical  experience  sustains  and  confirms  all  the  theoretical 
views,  and  the  deductions,  chemical  and  physiological,  which 
have  been  advanced  in  the  preceding  chapter.  To  a  few  of 
these  practical  confirmations  I  shall  briefly  advert. 

SECTION  I. — KIND  AND  QUANTITY  OF  FOOD  NECESSARY  TO  MAINTAIN 
A  HEALTHY  MAN. — PRISON  DIETARIES. — FOOD  REQUIRED  BY  SHEEP 
AND  CATTLE, 

The  dietaries  of  prisons,  and  their  effects  on  the  bodily 
health  and  weight  of  the  prisoners,  afford  one  of  the  simplest 
methods  of  testing  the  influence  of  kind  and  quantity  upon  the 
nourishing  power  of  food.  In  such  establishments — though 
open  to  the  objection  that  the  prisoners  are  in  a  state  of  xm- 
usual  restraint — experiments  can  be  performed  so  much  more 
accurately,  and  on  so  much  larger  a  scale  than  elsewhere,  as 
to  make  them  worthy  of  a  very  considerable  amount  of  confi- 
dence. 

An  inquiry  lately  made  into  the  comparative  health  and  food 


SCOTCH  PRISON  DIETARIES, 


357 


of  the  inmates  of  the  Scotch  prisons,  has  afforded  very  inter- 
esting materials  for  proving  the  necessity  of  a  mixed  food,  and 
of  a  certain  minimum  proportion  of  that  kind  of  food  which  is 
supposed  especially  to  sustain  the  muscular  and  other  tissues. 

In  the  course  of  the  preceding  chapter  we  have  stated  : 

1°.  That  a  healthy  man  in  ordinary  circumstances  voids  daily 
about  half  an  ounce  of  nitrogen  in  his  urine  alone,  (p.  351.) 
To  supply  this  he  would  require  to  consume  three  ounces  of  dry 
gluten,  albumen,  or  flesh. 

2°.  That  altogether  he  gives  off  from  the  lungs,  skin,  and 
kidneys,  about  350  grains,  or  five-sevenths  of  an  ounce,  to  supply 
which  he  must  consume  about  five  ounces  of  the  same  materials, 
(p.  342.) 

But  in  a  state  of  temporary  confinement,  when  not  subjected 
to  hard  labor,  this  quantity  may  be  safely  diminished.  Yet 
even  here  there  is  a  limit  below  which  it  is  unsafe  to  go.  In 
the  Scotch  prisons  the  weight  of  food  is  given  to  prisoners  con- 
fined for  not  more  than  two  months,  and  not  subjected  to  hard 
labor,  is  uniformly  about  It  ounces,  and  the  proportion  of  glu- 
ten or  nitrogenous  food  contained  in  this  is  about  four  ounces. 
Where  this  proportion  is  maintained,  the  average  general  health 
and  weight  of  the  prisoners  improves  during  their  confinement. 
Where  the  contrary  is  the  case,  the  weight  diminishes,  and  the 
health  declines.  This  is  shown  in  the  following  tabular  view 
of  the  kinds  and  weight  of  food  given  in  five  of  the  Scotch 
prisons,  and  jts  effects  upon  the  weight  of  the  prisoners  : — 


I 

Jail. 

Food  giyen. 

Per-centage  of  pri- 
soners who  lost 
weight. 

Nitrogenous. 

Carbonaceous.     Total. 

Edinburgh, 

Glasgow, 

Aberdeen, 

Stirling, 

Dundee, 

4  oz. 
4.06 
3.98 
4.27 
2.75 

13  oz. 

12.58 

13.03 

13.4 

14 

17  oz. 
16.84 
17 

17.67 
16.75 

18  lost  IJ  lb.  each 
32.66    4        " 

1 32          4.2      " 

50          4.35    " 

851  THEIR  RESULTS 

This  table  shows  that,  with  the  Edinburgh  dietary  and  inan« 
agement,  12  per  cent  of  the  prisoners  either  maintained  or  in- 
creased their  weight,  while  only  18  per  cent  diminished  in 
weight,  and  that  only  to  the  small  extent  of  IJ  lb.  each.  In 
Glasgow  the  result  was  less  favorable,  though  even  there,  out 
of  nearly  500  prisoners,  only  one-third  diminished  in  weight. 

The  same  was  the  case  at  Aberdeen  and  Stirlhig  ;  so  that 
in  these  three  places  the  diet  may  be  regarded  as,  on  the  whole, 
sufficient.  But  in  Dundee,  one-half  of  the  prisoners  (50  per 
cent)  lost  weight  during  their  short  confinement  ;  and  the  cause 
is  obvious,  in  the  diminished  proportion  of  muscle-forming  food, 
which  in  this  case  was  reduced  to  2|,  in  place  of  four  ounces. 

And  it  is  an  interesting  fact,  as  marking  the  close  connection 
between  science  and  practice,  that  this  deterioration  in  the 
quality  of  the  diet  was  caused  by  the  suhstitution  of  molasses 
for  the  milk,  which  had  been  previously  distributed  to  the  pri- 
soners along  with  their  porridge  of  oatmeal.  Milk  is  rich  in 
nitrogenous  food,  while  molasses?  contains  none  ;  and  the  sub- 
stitution was  immediately  followed  by  a  perceptible  falling  off 
in  the  health  and  weight  of  the  prisoners.  So  general  are  the 
evils  which  may  arise  from  ignorance  or  disregard  of  scientific 
principles  in  a  single  director  or  directing  body.  The  appa- 
rently trivial  substitution  of  molasses  for  milk  brought  weakness 
and  want  of  health  on  the  inmates  of  an  entire  prison. 

In  the  feeding  of  other  animals,  similar  results  follow  from 
similar  inattention  to  the  requirements  of  animal  nature.  Of 
dry  hay  it  has  been  found,  in  practice,  that  cattle  and  sheep 
require  for  their  daily  food — 

An  ox  at  rest,  2  per  cent  of  his  live  weight 

. .     at  work,  2J     . . 

. .     fatting,  5       . .         at  first. 

..     half  fat,  4i 

. .     when  fat,  4 

Milch  cow,  3 
Sheep,  fiill  grown,  3 J 


FOOD  REQUIRED  BY  ANIMALS. 


359 


In  the  case  of  the  ox  the  daily  waste  or  loss  of  muscle  and 
tissue  requires  that  he  should  consume  20  to  24  ounces  of  glu- 
ten or  albumen,  which,  as  may  be  calculated  from  the  table 
given  in  a  subsequent  section,  (p.  364,)  will  be  supplied  by  any 
of  the  following  weights  of  vegetable  food  : — 


Meadow  hay. 

.       20  lb. 

Turnips, 

120  lb. 

Clover  hay, 

16" 

Cabbage, 

TO  " 

Oat  straw, 

.       110" 

Wheat  or  other  white  grain, 

11  " 

Pea  straw, 

12" 

Beans  or  pease, 

6  " 

Potatoes, 

60" 

Oil-cake, 

4  " 

Carrots, 

10" 

Or  instead  of  any  one  of  these,  a  mixture  of  several  may  be 
given,  with  the  best  results.  But  if  the  due  proportion  of  ni- 
trogenous food  be  not  given,  the  ox  will  lose  his  muscular 
strength,  and  will  generally  fail.  So  with  growing  and  fatting 
stock  of  every  kind,  the  proportion  of  each  of  the  kinds  of  food 
required  by  the  animal  must  in  practice  be  adjusted  to  t^o 
purpose  for  which  it  is  fed,  as  theory  indicates,  or  actual  money 
loss  will  ensue  to  the  feeder. 


SECTION  II. 


-PRACTICAL  VALUE  OF    SALINE  AND    OTHER  INGREDIENTS 
OF  MILK  IN  FEEDING  THE  GROWING  CALF. 


In  the  course  of  the  preceding  section  I  have  incidentally 
remarked,  that  the  substitution  of  molasses  for  milk  lowered 
the  proportion  of  nitrogenous  food  in  the  Dundee  prison  diet, 
and  rendered  it  insuflQcient  for  the  healthy  maintenance  of  the 
prisoners.  The  reason  of  this  appears  in  the  composition  of 
milk,  already  given  in  a  previous  chapter.  The  consideration 
of  milk  as  a  natural  food  supplies  us  with  another  beautiful 
practical  illustration  of  our  theoretical  principles,  to  which  I 
shall  briefly  advert  ;  and  I  do  so,  not  merely  because  of  the 
light  it  throws  upon  the  supply  of  nitrogen  which  a  milk  diet  is 
fitted  to  yield,  but  because  it  so  clearly  illustrates  another  of 
the  positions  laid  down  in  the  preceding  chapter,  that  the  food 


360  MILK  A  TRUE  FOOD. 

must  supply,  in  kind  and  quantity,  all  the  saline  and  earthy 
substances  contained  in  the  body. 

Milk  is  a  true  food.  It  contains  sugar,  casein,  saline  mat- 
ter, and  fat — a  portion  of  each  of  those  classes  of  substances 
on  which  the  herbivorous  races  live  in  the  most  healthy  man 
ner.  But  the  provision  is  very  beautiful  by  which  the  young 
animal — the  muscle  and  bones  of  which  are  rapidly  growing — 
is  supplied,  not  only  with  a  large  proportion  of  nitrogenous 
food,  but  also  of  bone-earth,  than  would  be  necessary  to  main- 
tain the  healthy  condition  of  a  full-grown  animal  of  equal  size. 
The  inilk  of  the  mother  is  the  natural  food  from  which  its  sup- 
plies are  drawn.  The  sugar  of  the  milk  supplies  the  compara- 
tively small  quantity  of  carbon  necessary  for  the  respiration  of 
the  young  animal.  As  it  gets  older,  the  calf  or  young 
lamb  crops  green  food  for  itself,  to  supply  an  additional  portion. 
The  curd  of  the  milk  (casein)  yields  the  materials  of  the  grow- 
ing muscles  and  of  the  organic  part  of  the  bones  ;  while  along 
with  the  curd,  and  dissolved  in  the  liquid  milk,  is  the  phosphate 
of  lime,  of  which  the  earthy  part  of  the  bones  is  to  be  built 
up.  A  glance  at  the  composition  of  milk  will  show  how  copi- 
ous the  supply  of  all  these  substances  is, — how  beautifully  the 
composition  of  the  mother's  milk  is  adapted  to  the  wants  of  her 
infant  offspring.  Cow's  milk  consists  in  1000  parts  by  weight 
of  about — 

Butter, 21 

Cheesy  matter,  (casein,) 45 

Milk-sugar, 36 

Chloride  of  potassium,  and  a  little  common  salt,    .  14 

Phosphates,  chiefly  of  lime, 24 

Other  saline  substances, 6 

Water, .        .        .  882i 

1000 

The  quality  of  the  milk,  and  consequently  the  proportions  of 
the  several  constituents  above  mentioned,  vary,  as  I  have  ex- 
plained in  a  preceding  chapter,  with  the  breed  of  the  cow — 


DAIRY  HUSBANDRY  AFFECTS  THE  SOIt  361 

with  the  food  on  which  it  is  supported — with  the  time  that  has 
elapsed  since  the  period  of  calving — with  its  age,  its  state  oi 
health,  and  with  the  warmth  of  the  weather;*  but  in  all  cases 
this  fluid  contains  the  same  substances,  though  in  different 
quantities  and  proportions. 

Milk  of  the  quality  above  analysed  contains,  in  every  10  gal- 
lons, 4^  lb.  of  casein,  equal  to  the  formation  of  18  lb.  of  ordi- 
nary muscle, — and  3^  ounces  of  phosphate  of  lime,  (bone- 
earth,)  equal  to  the  production  of  *l  ounces  of  dry  bone.  But 
from  the  casein  have  to  be  formed  the  skin,  the  hair,  the  horn, 
the  hoof,  &c.,  as  well  as  the  muscle  ;  and  in  all  these  is  con- 
tained also  a  minute  quantity  of  the  bone-earth.  A  portion  of 
all  the  ingredients  of  the  milk  likewise  passes  off  in  the  ordi- 
nary excretions,  and  yet  every  one  knows  how  rapidly  young 
animals  thrive,  when  allowed  to  consume  the  whole  of  the  milk 
which  nature  has  provided  as  their  most  suitable  nourish- 
ment. 


SECTION  in. — EFFECT  OF  LONG-CONTINUED  DAIRY  HUSBANDRY  UPON 
THE  QUALITY  AND  PRODUCE  OF  THE  SOIL. 

And  whence  does  the  mother  derive  all  this  gluten  and  bone- 
earth,  by  which  she  can  not  only  repair  the  natural  waste  of 
her  own  full-grown  body,  but  from  which  she  can  spare  enough 
also  to  yield  so  large  a  supply  of  nourishing  milk  ? 

She  must  extract  them  from  the  vegetables  on  which  she 
lives,  and  these  again  from  the  soil. 

The  quantity  of  solid  matter  thus  yielded  by  the  cow  in  her 
milk  is  really  very  large,  if  we  look  at  the  produce  of  an  entire 
year.  If  the  average  yield  of  milk  be  3000  quarts,  or  750 
gallons,  in  a  year,  (every  10  gallons  of  which  contain  bone- 
earth  enough  to  form  about  *l  ounces  of  dry  bone,)  then  by  the 

*  In  warm  weather  the  milk  contains  more  'butter,  in  cold  weather  moro 
cheese  and  sugar. 


362  BY  REMOVING  BONE-EARTH. 

milking  of  the  cow  alone  we  draw  from  her  the  earthy  ingre- 
dients of  33  lb.  of  dry  bone  in  a  year.  These  are  equal  to  40 
lb.  of  common  bone-dust,  or  3  J  lb.  in  a  month.  And  these 
she  draws  necessarily  from  the  soil. 

If  this  milk  be  consumed  on  the  spot,  then  all  returns  again 
to  the  soil  on  the  annual  manuring  of  the  land.  Let  it  be 
carried  for  sale  to  a  distance,  or  let  it  be  converted  into  cheese 
and  butter,  and  in  this  form  exported — ^there  will  then  be 
yearly  drawn  from  the  land  from  this  cause  alone  a  quantity  of 
the  materials  of  bones  which  can  only  be  restored  by  the  ad- 
dition of  40  lb.  of  bone-dust  to  the  land.  If  to  this  loss  from 
the  milk  we  add  only  10  lb.  for  the  bone  carried  off  by  the 
yearly  calf,*  the  land  will  lose  by  the  practice  of  dairy  hus- 
bandry as  much  bone-earth  as  is  contained  in  50  lb.  of  bone- 
dust— or  in  45  years  every  imperial  acre  of  land  will  lose  what 
is  equivalent  to  a  ton  of  bones. 

After  the  lapse  of  centuries,  therefore,  we  can  easily  under- 
stand how  old  pasture  lands,  in  cheese  and  dairy  countries,  should 
become  poor  in  the  materials  of  bones — and  how  in  such  dis- 
tricts, as  is  now  found  to  be  the  case  in  Cheshire,  the  applica- 
tion of  bone-dust  should  entirely  alter  the  character  of  the 
grasses,  and  renovate  the  old  pastures. 

SECTION  IV. — OP   THE    GROWING    OF  WOOL,  AND   ITS    EFFECTS  UPON 
THE  SOIL. 

The  rearing  of  wool  affords  another  beautiful  practical  illus- 
tration, both  of  the  kind  of  food  which  animals  require  for  par- 

*  It  has.  been  estimated  that  the  proportion  of  bone  in  the — 

Horse —  .125  of  the  live  weight. 

Sheep,  old,  (Merino,)  .        .        — »  .125  of  live,  20  of  dead  da 
^  .33  nearly,  of  flesh  and  fat 
Pig,  unfatted,     .        .        .        —  .17  of  live,  .20  of  cfead  do. 
And  generally,  that  100  Uve  weight  indicate  2  to  3  of  phosphoric  acid ;  but 
these  proportions  are,  no  doubt,  subject  to  great  variation. 


LONG  GROWTH  OP  WOOL  ON  THE  LAND.  863 

ticnlar  purposes,  and  of  the  effect  wMch  a  peculiar  husbandry 
must  slowly  produce  upon  the  soil. 

Wool  and  hair  are  distinguished  from  the  fleshy  parts  of  the 
animal  by  the  large  proportion  of  sulphur  they  contain.  Per- 
fectly clean  and  dry  wool  contains  about  5  per  cent  of  sulphur, 
or  every  100  lb.  contains  5  lb. 

The  quantity  as  well  as  the  quality  of  the  wool  yielded  by  a 
single  sheep  varies  much  with  the  breed,  the  climate,  the  con- 
stitution, the  food,  and  consequently  with  the  soil  on  which  the 
food  is  grown.  The  Hereford  sheep,  which  are  kept  lean,  and 
give  the  finest  wool,  yield  \only  1^  lb. ;  but  a  Merino  often 
gives  a  fleece  weighing  10  or  11  lb.,  and  sometimes  as  much  as 
12  1b. 

The  number  of  sheep  in  Great  Britain  and  Ireland  amounts 
to  30  millions,  and  their  yield  of  wool  to  111  millions  of 
pounds,  or  about  4  lb.  to  the  fleece.  This  quantity  of  wool 
contains  5  millions  of  pounds  of  sulphur,  which  is  of  course  all 
extracted  from  the  soU. 

If  we  suppose  this  sulphur  to  exist  in,  and  to  be  extracted 
from,  the  soU  in  the  form  of  gypsum,  then  the  plants  which  the 
sheep  live  upon,  must  take  out  from  the  soil,  to  produce  the 
wool  alone,  30  millions  of  pounds,  or  13,000  tons  of  gypsum. 

Now,  though  the  ptoportion  of  this  gypsum  lost  by  any  one 
sheep  farm  in  a  year  is  comparatively  small,  yet  it  is  reasonable 
to  believe  that,  by  the  long  growth  of  wool  on  hilly  land,  to 
which  nothing  is  ever  added,  either  by  art  or  fiom  natural 
sources,  those  grasses  must  gradually  cease  to  grow  in  which 
sulphur  most  largely  abounds,  and  which  favor,  therefore,  the 
growth  of  wool.  In  other  words,  the  produce  of  wool  is 
likely  to  diminish,  by  lapse  of  time,  where  it  has  for  centuries 
been  yearly  carried  off  the  land;  and,  again,  this  produce  is 
likely  to  be  increased  in  amount  when  such  land  is  dressed  with 
gypsum,  or  with  other  manure  in  which  sulphur  naturally  ex- 
ists.   Of  course,  this  general  conclusion  will  not  apply  to  lo« 


864 


PRACTICAL  AND  THEOKETICAL  VALUES 


calities  wWch  derive  from  springs  or  other  natural  sourcea  a 
supply  of  sulphur  equal  to  that  which  is  yearly  removed. 

SECTION  V. OF  THE   PRACTICAL   AND   THEORETICAL  VALUES  OP   DIF- 
FERENT KINDS  OP  FOOD. 

From  what  has  been  stated  in  the  preceding  sections,  it  ap- 
pears, as  the  result  both  of  theory  and  of  practice,  that  dif- 
ferent kinds  of  food  are  not  equally  nourishing.  This  fact  is  ot 
great  importance,  not  only  in  the  preparation  of  human  food, 
but  also  in  the  rearing  and  fattening  of  stock.  It  has,  there* 
fore,  been  made  the  subject  of  experiment  by  many  practical 
agriculturists,  with  the  following  general  results  : 

1.  If  common  hay  be  taken  as  the  standard  of  comparison, 
then,  to  yield  the  same  amount  of  nourishment  as  14  lb.  of  hay, 
experiments  on  feeding  made  by  different  persons,  and  in  dif- 
ferent countries,  say  that  a  weight  of  the  other  kinds  of  food 
must  be  given,  which  is  represented  by  the  number  opposite  to 
each  in  the  following  table  : — 


Hay, 

10 

Carrots,  (white,) 

45 

Clover  hay. 

8  to  10 

Mangold-wurtzel, 

35 

Green  clover, 

45  "  50 

Turnips, 

50 

"Wheat  straw, 

40  "  50 

Cabbage, 

20  " 

30 

Barley  straw, 

20  "  40 

Pease  and  beans, 

3  " 

6 

Oat  straw, 

20  "  40 

Wheat,  . 

5  " 

6 

Pea  straw, 

10  "  15 

Barley,  • 

5  " 

6 

Potatoes, 

20 

Oata,      . 

4  " 

1 

Old  potatoes 

40? 

Indian  com,   . 

5 

Carrots,  (red) 

25  "  30 

Oil-cake, 

2  " 

4 

It  is  found  in  practice,  as  the  above  table  shows,  that 
twenty  stones  of  potatoes,  or  three  of  oil-cake,  will  nourish  an 
animal  as  much  as  ten  stones  of  hay  will,  and  5  stones  of  oats 
as  much  as  either.  Something,  however,  will  depend  upon  the 
quality  of  the  sample  of  each  kind  of  food  used — which  we 
know  varies  very  much,  and  with  numerous  circumstances;  and 
something  also  upon  the  age  and  constitution  of  the  animal. 


OF  DIFFERENT  KINDS  OF  FOOD. 


365 


and  upon  the  way  and  form  in  which  the  food  is  administered. 
The  skilful  rearer,  feeder,  and  fattener  of  stock  knows  also  the 
value  of  a  change  of  food,  or  of  a  mixture  of  the  different 
kinds  of  vegetable  food  he  may  have  at  his  command — a  sub- 
ject we  have  considered  in  a  previous  section. 

2.  The  generally  nutritive  value  of  diflferent  kinds  of  food 
has  also  been  represented  theoretically,  by  supposing  it  to  be 
very  nearly  in  proportion  to  the  quantity  of  nitrogen,  or  of 
gluten,  which  vegetables  contain.  Though  this  cannot  be  con- 
sidered as  a  correct  principle,  yet  as  the  ordinary  kinds  of  food 
on  which  stock  is  fed  contain  in  general  an  ample  supply  of 
carbon  for  respiration,  with  a  comparatively  small  proportion 
of  nitrogen,  these  theoretical  determinations  are  by  no  means 
without  their  value,  and  they  approach,  in  many  cases,  very 
closely  to  the  practical  values  above  given,  as  deduced  from 
actual  trial.  Thus  assuming  that  10  lb.  of  hay  yield  a  certain 
amount  of  nourishment,  then  of  the  other  vegetable  substances 
it  will  be  necessary,  according  to  theory,  to  give  the  following 
quantities,  in  order  to  produce  the  same  general  effect  iu 
feeding  : — 


Hay,    .        . 
Clover  hay,* 
Vetch  hay, 
"Wheat  straw, 
Barley  straw, 
Oat  straw, 
Pea  straw. 
Potatoes, 
Old  potatoes, 
Turnips, 
Mangold-wurtzel, 


10 

8 

4 

52 

52 

55 

6 

28 

40 

60 

50 


Carrots,  (red,).    . 
Cabbage,     . 
Pease  and  beans. 

35 

30  to  40 
2  to    3 

Wheat, 

5 

Barley, 
Oats, 
Rye, 
Indian  com. 

6 
6 
5 
6 
5 
2 

Bran, 
Oil-cako, 

If  the  feeder  be  careful  to  supply  his  stock  with  a  mixture  or 
occasional  change  of  food — and  especially,  where  necessary, 
with  a  proper  proportion  of  fatty  matter — he  may  very  safely 
regulate,  by  the  numbers  in  the  above  tables,  the  quantity  oi 


*  Both  cut  in  flower. 


366  ON  WHAT  THE  FATTENING  PROPERTY 

any  one  which  he  ought  to  substitute  for  a  given  weight  of  any 
of  the  others — since  the  theoretical  and  practical  results  do  not 
in  general  very  greatly  diflfer.    " 

3.  As  has  been  already  stated,  however,  it  is  not  strictly  cor« 
rect  that  this  or  that  kind  of  vegetable  is  more  fitted  to  sustain 
animal  life,  simply  because  of  the  large  proportion  of  nitrogen 
or  gluten  it  contains;  but  it  is  wisely  provided  that,  along  with 
this  nitrogen,  all  plants  contain  a  certain  proportion  of  starch 
or  sugar,  and  of  saline  and  earthy  matter — all  of  which,  as  we 
have  seen,  are  required  in  a  mixture  which  will  most  easily  sus- 
tain an  animal  in  a  healthy  condition;  so  that  the  proportion 
of  nitrogen  in  a  substance  may  be  considered  as  a  rough  prao- 
tical  index  of  the  proportion  of  the  more  important  saline  and 
earthy  ingredients  also. 

4.  It  is  very  doubtful,  however,  how  far  this  proportion  of 
nitrogen  can  be  regarded  as  any  index  of  the  fattening  pro- 
perty of  vegetable  substances.  If  the  fat  in  the  body  be  pro- 
duced from  the  oil  in  the  food,  it  is  certain  that  the  proportion 
of  this  oil  in  vegetable  substances  is  by  no  means  regulated  by 
that  of  the  gluten  or  other  analogous  substances  containing  ni- 
trogen. The  stock  farmer  who  wishes  to  lay  on  fat  only  upon 
his  animals,  must  therefore  be  regulated  by  another  principle. 
He  must  select  those  kinds  of  food,  such  as  linseed  and  oil- 
cake, in  which  fatty  matters  appear  to  abound,  or  mix,  as  I 
have  already  said,  (p.  354,)  a  due  proportion  of  fat  or  oil  with 
the  other  kinds  of  food  he  employs. 

But  large  quantities  of  fat  accumulate  in  the  bodies  of  most 
animals,  only  when  they  are  in  an  unnatural,  and,  perhaps  in 
some  measure,  an  unhealthy  condition.  In  a  state  of  nature 
there  are  comparatively  few  animals  upon  which  large  accumu- 
lations of  fat  take  place.  A  certain  portion,  as  we  have  seen, 
is  necessary  to  the  healthy  animal ;  but  it  is  an  interesting 
fact,~~that  as  much  as  is  necessary  to  supply  this  is  present  in 
most  kinds  of  vegetable  food.  In  wheaten  flour  it  is  asso- 
ciated with  the  gluten,  and  may  be  extracted  from  it  after  the 


OF  FOOD  DEPEND^.  367 

starch  of  the  flour  has  been  separated  from  the  giiiten  by 
washing  with  water,  as  already  described  (pp.  40  and  45.)  In 
so  far,  therefore,  as  this  comparatively  small  necessary  quantity 
of  fatty  matter  is  concerned,  the  proportion  of  nitrogen  may 
also  be  taken,  without  the  risk  of  any  serious  error,  as  a  prac- 
tical indication  of  the  ability  of  the  food  to  supply  the  natural 
waste  of  fat  in  an  animal  which  is  either  growing  in  general 
size  only,  or  is  only  to  be  maintained  in  its  existing  condition. 

While,  therefore,  it  appears  from  the  study  of  the  principles 
upon  which  the  feeding  of  animals  depends,  that  a  mixture  of 
various  principles  is  necessary  in  a  nutritive  food,  it  is  interest- 
ing to  find  that  all  the  kinds  of  vegetable  food  which  are 
raised,  either  by  art  or  by  natural  growth,  are  in  reahty  such 
mixtures  of  these  several  substances — more  or  less  adapted  to 
fulfil  all  the  conditions  required  from  a  nutritious  diet,  accord- 
ing to  the  state  of  health  and  growth  in  which  the  animal  to 
be  fed  may  happen  to  be. 

An  important  practical  lesson  on  this  subject,  therefore,  is 
taught  us  by  the  study  of  the  wise  provisions  of  nature.  Not 
only  does  the  milk  of  the  mother  contain  all  the  elements  of  a 
nutritive  food  mixed  up  together — as  the  egg  does  also  for  the 
unhatched  bird — ^but  in  rich  natural  pastures  the  same  mixture 
uniformly  occurs.  Hence,  in  cropping  the  mixed  herbage,  the 
animal  introduces  into  its  stomach  portions  of  various  plants — 
some  abounding  more  in  starch  or  sugar,  some  more  in  gluten 
or  albumen — some  more  in  fatty  matter — while  some  are  natu- 
rally richer  in  saline,  others  in  earthy  constituents  ;  and  out  of 
these  varied  materials  the  digestive  organs  select  a  due  propor- 
tion of  each  and  reject  the  rest.  Wherever  a  pasture  becomes 
usurped  by  one  or  two  grasses — either  animals  cease  to  thrive 
upon  it,  or  they  must  crop  a  much  larger  quantity  of  food  to 
supply  from  this  one  grass  the  natural  waste  of  all  the  parts  of 
their  bodies. 

It  may  indeed  be  assumed  as  almost  a  general  pj-incipje,  that 
whenever  animals  are  fed  on  one  kind  of  vegetable  only,  there 


868  COMPARATIVE  PRODUCE  OF  BEEF  AND  MILK. 

is  a  waste  of  one  or  other  of  the  necessary  elements  of  animal 
food,  and  that  the  great  lesson  on  this  subject  taught  us  by  na- 
ture is,  that  by  a  judicious  admixture,  not  only  is  food  economist 
ed,  hut  the  labor  imposed  upon  the  digestive  organs  is  also  Tnateri- 
ally  diminished. 

SECTION  VI. ^RELATIVE  PROPORTIONS  OF  FOOD  FOR  MAN   YIELDED  BY 

THE  SAME  HERBAGE  IN  THE  FORMS  OF  BEEF  AND  MILK. 

A  curious  economical  question,  in  connection  with  the  value 
of  vegetable  produce  in  feeding  cattle,  presents  itself  to  us 
when  we  come  to  compare  the  proportions  of  human  food  which 
may  be  obtained  from  the  same  weight  of  herbage  when  cattle 
are  fed  with  it  for  diflferent  immediate  purposes. 

A  ton  of  hay  may  be  given  to  a  bullock  to  be  converted 
into  beef.  Another  ton  of  the  same  hay  may  be  given  to  a 
cow  to  be  converted  into  milk.  Would  the  beef  or  the  milk 
produced  contain  the  larger  supply  of  food  for  man  ?  We  have 
rather  imperfect  data  to  rely  upon  in  answering  this  question, 
but  they  lead  us  to  very  interesting  results. 

1.  According  to  Sir  John  Sinclair,  the  same  herbage  which 
will  add  112  lb.  to  the  weight  of  an  ox,  will  enable  a  cow  to 
yield  450  wine  gallons,  or  3600  lb.  of  milk.  This  milk  will 
contain  160  lb.  of  dry  curd,  160  lb.  of  butter,  180  lb.  of  sugar, 
and  18  lb.  of  saline  matter,  while  the  112  lb.  of  beef  will  not 
contain  more  than  25  lb.  or  30  lb.  of  dry  muscle,  fat,  and  sa- 
line matter  together  ;  that  is  to  say,  the  same  weight  of  herb- 
age which  will  produce  less  than  30  lb.  of  dry  human  food  in 
the  form  of  beef,  will  yield  500  lb.  in  the  form  of  milk. 

2.  But  this  statement  of  Sir  John  Sinclair's  is,  I  fear,  not  to 
be  relied  upon.  We  have  another,  however,  something  diflfer- 
ent, from  Riedesel,  a  Continental  authority.  He  says  that  the 
same  quantity  of  hay  will  produce  either  100  lb.  of  beef,  or 
100  imperial  gallons  (1000  lb.)  of  milk.     This  quantity  of 


CIRCUMSTANCES  MODIFY  369 

milk  contains  only  150  lb.  of  dry  food,  but  it  is  still  five  times 
as  much  as  is  contained  in  the  beef. 

This  statement  of  Riedesel  is  also  to  be  received  with  hesita- 
tion ;  bnt  the  subject  is  interesting  and  important,  as  well  as 
curious,  and  is  deserving  of  further  investigation.  Should  the 
population  of  the  country  ever  become  so  dense  as  to  render  a 
rigorous  economy  of  food  a  national  question,  butcher-meat,  if 
the  a])Ove  data  deserve  any  reliance — will  be  banished  from 
our  tables,  and  a  milk  diet  will  be  the  daily  sustenance  of  al- 
most all  classes  of  society. 

SECTION    VII. INFLUENCE    OF    CIRCUMSTANCES    IN    MODIFYING  THB 

PRACTICAL  VALUES  OF  ANIMAL  AND  VEGETABLE  FOOD. 

The  indications  of  theory,  and  the  results  of  general  prac- 
tice, in  regard  to  the  nutritive  power  of  different  vegetable 
substances,  are  modified  by  many  circumstances  which  ought  to 
be  borne  in  mind.  Whether  fed  for  work,  or  for  the  produc- 
tion of  flesh  or  milk,  the  effect  of  the  food  given  to  animals  will 
depend  partly  on  the  kind,  breed,  and  constitution  of  the  ani- 
mal itself — on  the  general  treatment  to  which  it  is  subjected, 
and  the  place  in  which  it  is  kept — on  its  size  and  state  of  health 
— and  on  the  form  in  which  the  food  itself  is  given. 

1.  Tht  breed  or  constitution,  every  feeder  knows,  has  a  great 
influence  on  the  apparent  value  of  food.  Some  breeds,  like  the 
improved  short-horn,  have  a  natural  tendency  to  fatten,  which 
makes  them  increase  in  weight  more  rapidly  than  other  breeds, 
when  fed  upon  the  same  food.  And  even  in  the  same  breed, 
the  rapidity  with  which  one  animal  lays  on  flesh  will  sometimes 
make  it  two  or  three  times  more  profitable  to  the  farmer  than 
others  which  are  fed  along  with  it. 

2.  Warmth  and  shelter  cause  the  same  amount  of  food  to  go 
farther,  as  do  also  gentle  treatment  and  the  absence  of  glaring 
light.  Sheep  have  produced  double  the  weight  of  mutton 
from  the  same  weight  of  vegetable  food,  when  fed  under  shel- 


8t6  THE  PRACTICAL  VALU^  OF  FOOD, 

ter,  and  kept  undisturbed  and  in  the  dark.  It  is  probably  from 
this  beneficial  influence  of  warmth  that,  in  the  I^orth  American 
states,  a  difference  of  25  per  cent  is  observed  in  favor  of  the 
spring  and  summer  over  the  winter  feeding  of  the  pigs  upon 
similar  food. 

3.  The,  form  in  which  the  food  is  given  is  of  no  less  importance. 
Grass  newly  cut  goes  farther  than  after  it  is  made  into  hay; 
and  the  opinion  is  now  becoming  very  generally  prevalent, 
that  steamed,  boiled,  or  otherwise  prepared  food,  is  more  whole- 
some for  cattle,  and  more  economical  to  the  feeder,  than  the 
same  food  given  in  a  dry  state. 

In  the  case  of  horses,  the  difference  between  the  practice  of 
giving  all  the  food  dry  and  uncut,  and  that  of  giving  all  the 
hay  cut  with  the  oats  and  beans  crushed,  and  an  evening  meal 
of  steamed  food,  is  such  as  to  effect  a  saving  of  nearly  one- 
third.  Thus,  the  same  waggon  horses  which  consumed  3J 
bushels  of  oats  per  week,  and  14  stones  of  hay,  when  given 
uncut,  uncrushed,  and  uncooked,  were  kept  in  good  condition 
by  2J  bushels  of  oats,  8  stones  of  hay,  and  1  lb.  of  linseed 
when  the  grain  was  crushed,  the  hay  cut  into  half-inch  chaff, 
and  the  linseed  with  a  little  bean-meal  and  cut  hay  made  into 
a  steamed  meal-feed  in  the  evening.* 

4.  The  malting  and  sprouting  of  barley  is  by  many  practical 
men  considered  to  increase  its  nutritive  qualities.  It  is  certain 
that,  when  mixed  with  boiled  potatoes  to  the  extent  of  three 
or  four  per  cent,  and  kept  warm  for  a  few  hours,  bruised  malt 
produces  a  prepared  food  which  is  much  relished  by  milch 
cows,  and  is  profitable  to  the  dairy-man.  There  is  reason  to 
believe  that  similar  mixtures  with  other  kinds  of  food  would 
produce  similar  beneficial  effects. 

Mr.  Hudson,  of  Castle  Acre,  feeds  his  farm-horses  on  12  Ibyof 
sprouted  barley  a-day,  besides  their  fodder  ;  and  this,  on  his 

*  The  dry  feeding  being — ^liay  12  lb.,  with  oats  and  beans  14  lb. ;  the 
steamed  feed — hay  3  lb.,  beans  3  lb.,  linseed  1  lb. — Caird's  English  Agri^ 
CuJMj/re,  p.  346. 


CONCLUDING  REMARKS.  371 

light  land,,  keeps  them  in  good  condition.  It  is  prepared  by 
steeping  the  barley  for  24  hours,  and  then  putting  it  into  a 
heap  and  turning  it  over  for  five  days.* 

5.  The  souring  of  food  of  all  kinds  has,  by  almost  universal 
consent,  been  found  to  make  it  more  profitable  in  the  feeding 
and  fattening  of  pigs.  It  makes  them  fatten  faster,  and  gives 
a  firmer  and  whiter  flesh. 

Many  other  circumstances  also  modify  the  real  practical 
value  of  food,  and  cause  it  to  produce  results  different  from 
those  indicated  by  its  chemical  composition.  But  to  those, 
want  of  space  does  not  permit  me  here  to  advert. 

SECTION  VIII. — CONCLUDING  REMARKS. 

In  the  little  work  now  brought  to  a  close,  I  have  presented 
the  reader  with  a  brief,  but  I  hope  plain  and  familiar  sketch  of 
the  various  topics  connected  with  Practical  Agriculture,  on 
which  the  sciences  of  Chemistry,  Geology,  and  Chemical  Phy- 
siology are  fitted  to  throw  the  greatest  light. 

We  have  studied  the  general  characters  of  the  organic  and 
inorganic  elements  of  which  the  parts  of  plants  are  made  up, 
and  the  several  compounds  of  these  elements  which  are  of  the 
greatest  importance  in  the  vegetable  kingdom.  We  have  exa- 
mined the  nature  of  the  seed — seen  by  what  beautiful  pro- 
vision it  is  fed  during  its  early  germination — in  what  forms  the 
elements  by  which  it  is  nourished  are  introduced  into  the  cir- 
culation of  the  young  plant  when  the  functions  of  the  seed  are 
discharged — and  how  earth,  air,  and  water,  are  all  made  to 
minister  to  its  after-growth.  We  have  considered  the  various 
chemical  changes  which  take  place  within  the  growing  plant 
during  the  formation  of  its  woody  stem,  the  blossoming  of  its 
flower,  and  the  ripening  of  its  seed  or  fruit, — and  have  traced 
the  further  changes  it  undergoes,  when,  the  functions  of  its 

*  Oairds  English  Agriculture,  p.  IGS. 


872  CONCLUDING  REMARKS. 

short  life  being  discharged,  it  hastens  to  serve  other  par^o^es, 
by  mingling  with  the  soil,  and  supplying  food  to  new  races. 
The  soils  themselves  in  which  plants  grow,  their  nature,  their 
origin,  the  causes  of  their  diversity  in  mineral  character,  and 
in  natural  productiveness,  have  each  occupied  a  share  of  our 
attention — ^while  the  various  means  of  improving  their  agricul- 
tural value  by  mechanical  means,  by  manuring  or  otherwise, 
have  been  practically  considered,  and  theoretically  explained. 
Lastly,  we  have  glanced  at  the  comparative  worth  of  the  va- 
rious products  of  the  land  as  food  for  man  or  other  animals, 
and  have  briefly  illustrated  the  principles  upon  which  the  feed- 
ing of  animals,  and  the  relative  nutritive  powers  of  the  vegeta- 
bles on  which  they  live,  and  of  the  parts  of  animal  bodies 
themselves,  are  known  to  depend. 

In  this  short  and  familiar  treatise  I  have  not  sought  so  much 
to  satisfy  the  demands  of  the  philosophical  agriculturist,  as 
to  awaken  the  curiosity  of  my  less  instructed  reader,  to  show 
him  how  much  interesting  as  well  as  practically  useful  informa- 
tion Chemistry  and  Geology  are  able  and  willing  to  impart  to 
him,  and  thus  to  allure  him  in  quest  of  further  knowledge  and 
more  accurate  details  to  my  larger  work,*  of  which  the  present 
exhibits  only  a  brief  outline. 

*  Lectures  on  Agricultural  Chemistry  and  Oeology. 


THE  END. 


ALPHABETICAL  AifB  AKALTHCAl 


INDEX. 


Aero,  Carbonic,         .  18,  32 

"     Humic,  ...       21 

"     Geic,       ....    21 

"      Crenic,        ...  22 

"      Apo-Crenic,     .        .  .22 

"      Nitric,        ....  29 

"      Sulphuric,       ...      33 

"      Phosphoric,         .         .  34 

"      Pectose,  pectic,       .        .      44 

"      of  milk,  how  produced,       327 

Acorn,  composition  ot,        .         289 

Agriculture,  a  chemical  art,         133 

Albumen,  .        .        .46,  342 

Alumina,         .         .         .         .56 

Ammonia,  its  properties,      .  26 

"  nitrate  of,         .         .      30 

"  salts  of;  as  maniires,    222 

"         carbonate  o(|        .        223 

"         sulphate  ofj       .       .    224 

"         salts  of,  experiments 

with,        .        .         225 
Animals,  organic  parts  ofj        .      14 
"        main  visible  functions 

oC,  .  .  .  337 
"  respiration  of,  .  .338 
"  carbon  given  ofif  by,  339 
"  bones  of;  .  .  346 
"        kind  of  food  required  by,  3  5  9 


Analysis  of  organic  parts  of 
plants, 
"        of  barley,  wheat,  oats, 
beans,    rye,    corn, 
linseed,  potato,  and 
turnip, 
"        of  guano,     . 
"        of  experiments  with 
salts  of  ammonia, 
"        of  carbon  and  nitro- 
gen taken  in  food 
and  respired, 
"        of  soils, 
"        of  water. 
Aquafortis,  (nitric  acid,) 
Ash,  of  wood  and  grain, 
"    of  wheat  and  oat  straw, 
wheat  leaves,  oats,  oak 
wood,   animal  substan- 
ces, and  bones,       .        .     T 
quantity  of  lefl  by  plants,       59 
"         of  in  different  plants,  59 
quality  of,        .        .        .     64 
of  grains,  table  o^        .  64 

quantity  of  depends  on  the 

soil,     .        .        .        63,  67 
of  straw,  table  o^        .  68 

of  crab  apple  tree,  .      67 

of  wheat,  table  o^       .  68 

of  wood  and  straw,         .     232 


14 


64 
208 


225 


217 

263 

274 

29 

6 


su 


INDEX. 


Ash,  of  bushels  of  oats,  barley, 

and  rice,        .        .  233 

"    of  peat  and  coal,  .       234 

Atmosphere,  composition  of,      .    32 


B. 

Barley,  composition  o^        .        284 

"      malting  qualities  of,      .    285 

"      feeding  qualities  of,  286 

"      varying  qualities  o^  290 

"      oil  in  100  lbs.  of,      .         307 

Bean,  composition  of|        .        .  288 

Beef;  and  milk,     ...        368 

Blood,  kind  of  food  required,  ^s 

indicated  by  the,        .    352 
"      what  it  teaches,        .        353 
Body,  muscular  parts  of  the,     .    341 
"      mineral  matter  in  the,         345 
Bran,  value  of,        .        .         .176 
Bromides,  ...  59 

Bromine,        ...  .58 

Bones,  dry,  6  per  cent,  phospho- 
rus, ...         14 
"      pomposition  of  and  value 

as  manure,        .        .192 
"      to  dissolve  with  acid,         194 
"      experiments  with,        .     195 
Buckwheat,  composition  o^  287 

Butter,  quality  of  varies,  .     322 

"      composition  of)        .  323 

"      preservation  o^  .324 

"      why  it  becomes  rancid,     325 
"     coloring  o^        .        .       326 


a 


Cabbage,  composition  o^  .  300 
Carbon,  ....  218 
Carbonate  of  potash  and  soda,  226 
"  of  magnesia  in  lime- 
stone, ,  .  252 
Casein,  .  .  .  ,46,  342 
Cauliflower,  qualities  of,  .  301 
Chalk,  in  Aiabama,                   .  114 


Charcoal,  uses  of|     .        .  181 

Cheese,  manufacture  of|        .       331 
"         quality  of,  .         .    332 

"        varieties  ofj      .        .        333 
"        cream,  cream  and  milk, 
whole   or   full   milk, 
half  milk,    skimmed 
milk,         .        .  334 

"        whey,  butter-milk,  veg- 
etable and  potato,       325 
Chemistry,  what  it  will  do  for 

agriculture,        •        1 
Chlorides,  how  formed,  .         58 

Chlorine,  .        .        .        .57 

Churning,  ...         319 

Clay,  influence  of  au",  frost,  and 

water  on,  .        •      142 

"    sinks  in  the  soil,        .  151 

"    and  earth  burned,  .       269 

"    cause   of   the  mechanical 

and  chemical  action  of,     270 

Clover,  red  and  white,  what  soils      \ 

they  like,        .        .       136 

"      hay,  oil  in  100  lbs.  of,       307 

Coal  dust  and  coal  tar,        .         183 

Cocoanut  cake,        .        .        .178 

Corals,  shell-sand,  marls,      .        253 

Corn,  Indian,  composition  o^        287 

"      oil  in  100  lbs.  of         .        307 

Cream,  composition  of)     .        .319 

Crops,  why  one  may  grow  well 

where  another  fells,      .     72 

"       rotation  of  necessary,  72,132 

Curd,  why  it  separates,        .        329 


D. 


Dairy  husbandry,  effects  of  on 

the  soil,         .        .        .361 

Digestion,  effects  of  animal,  217 

Draining,  benefits  produced  by,    137 

"        of  light  soils,  ,  138 

"        summary  of  advantages 

of,        .        .        .      142 

"        depth  of,     -.        .        .142 

Dung,  value  ofj      .        .        .      218 

"      of  full-grown  animals,        213 


INDEX. 


315 


E. 

Bxperiments,  importance  of, 


Farmer,  object  of  the  practical,        1 
Fat,  waste  of  in  animals,        .      347 
"    purposes  served  by,      .        349 
Fermentation,  of  dry  vegetable 

matter,        .       174 

"  loss  of  weight  by,    175 

Fibrin,  composition  of,         .  342 

Fluorine,        ....        59 

Food,   quantity  yielded  by  an 

acre,        .       f.        .        308 
"     must  repair  daily  waste 

in  animals,        .        .      341 
"      must  supply  saline  and 

earthy  matters,  .  344 
"  importance  of  a  mixed,  353 
"  value  of  oily,  in  fatting,  355 
"  kind  and  quantity  neces- 
sary to  maintain  a  heal- 
thy man,  .  .  .  356 
"  given  prisoners,  .  .357 
"     required    by   sheep  an,d 

cattle,     ...  358 

"     practical  and  theoretical 

value  of;        .        .  364 

"     on  what  its  fattening  prop- 
erties depends,        .        366 
"      animal  and  vegetable,        369 
"     practical  value  of,        .      370 
"     form  in  which  it  is  given,  370 
"      the  souring  of,        .        .371 
Fork,  use  of  in  loosening  subsoil,  150 
Fruits,  composition  of,        .  302 

"      effects  of  soil   on  their 

quality  and  flavor,         303 


G. 


3ta,  Hydrogen, 
"    Oxygen, 
"    Nitrogen, 


Geology,  what  it  will  do  for  agri- 
culture,       .        .         1 
''       its  relations  to  agricul- 
ture,      .        .        8,  102 
"       value  of  "to  the  farmer^    88 
Gelatine,        ...        34,  342 
Gluten,      ....  342 

Grass,  laying  down  land  to,  159 

"      how  land  is  improved  by 

laying  down  to,        .       160 
"      roots  of  remaining  in  the 

soil,        .        .        .         161 
"      natural  changes,  .        .      16S 
Guano,  varieties  of,     .        .  205 

"      fertilizing  effects  o^  206 

"      composition  of  .      208 

"  permanence  of  action  oi^  209 
"  adulteration  of,  .  210 
"     how  to  select  good,  211 

"      national  value  oij        .     212 
"      artificial,    how  to    pre- 
pare,       .        .  248 
Gypsum,  taken  from  the  soil  by 

wool-growing,        .    363 

H. 

Hay  and  straw,        .        .  309 

"    time  of  cutting  affects  quan- 
tity and  quality  ofj        .    303 
"    clover,  oU  inlOO  lbs.  o^        30" 
"    meadow,  oil  ui  100  lbs.  of,  307 
Hemp,  poppy  and  cotton  cakes,   178 
Horn  and  hoof  parings  as  ma- 
nure,       .        .        ./        119 
Hydrogei;,  .        .  9 


Illustrations — 

Burning  the  soil,        .        .  6 

procuring  hydrogen  gas,    9,  10 

"      oxygen  gas,  11 

"      carbonic  acid,  18, 19,  20 

burning  hydrogen  gas,        .  24 

procuring  phosphoric  acid,  34 

pores  on  the  leaf  of  gardec 

balsam,        ...  3' 


8*76 


INDEX. 


■'•U.USTEATIONS — 

procuring  starch,  .  .  40 
starcli,  gluten  andfet  in  grain,  41 
procuring  chlorine,  .  57 
stratified  and  unstratified 

rocks,      ...  84 

section  of  coast  line,        .        91 

of  different  soils,      .     94,  95,  98 

of  drifts,  .         .        .113 

Inorganic  bodies,  .        .  6 

"    matter  carried  off  in  crops,    69 

Insects,  as  a  manure,        .        .189 

Iodine,  ....         58 

Iodides,  ....      59 

Iron,  oxide  or  rust  o^  .        140 

Irrigation,        .        .  .272 


220 


Land,  improvement  of  by  feed 

ing  sheep, 

Leaves,  how  they  fertQize       .     158 

"      of  turnips,  potatoes,  &c.,  171 

"      of  trees,  nutrition  ofj       301 

Lime,        .        .        .        .55,  155 

"    Nitrate  of,    ...        30 

"    sinks  in  the  soil,         150,  259 

"    phosphate  ofj  in  animals,    252 

"    burning  and  slaking  of, 

"    effects  of  exposure  of,  to 

the  air, 
"    effects  of  burning, 
"    quantity  usually  applied, 
"    visible  improvements  by, 
"    why  it  must  be  repeated, 
"    crops  and  rains  carry  it 

away, 

"    chemical  effects  of, 

"    exhausting  effects  ofj 

Limestones  and  chalks,  composi- 

tion  o^   . 

"         benefits  of  burning,  255 

Linseed,  and  linseed  cake,   .        287 

"      oil  ill  100  lbs.  of,         .     307 

Lungs,  carbon  given  off  by,        339 

"     the,    actually  feed    the 

body,   .   .   .340 


254 

255 
256 
257 
258 
268 

259 
260 
265 

250 


M. 


Magne 

sia,        .... 

66 

II 

nitrate  of, 

30 

11 

carbonate  ofj  in  lime- 

stone and  chalk, 

252 

Maize, 

(Indian  com),   composi- 

tion of  . 

287 

Malt-dust, 

177 

Manure,   acQurate  knowledge 

of,        .        .        . 

3 

II 

artificial,  why  necessary, 

71 

11 

what  is  a, 

168 

<i 

use  of  vegetable,   . 

168 

It 

relative  fertilizmg  and 
money  values  of  dif- 

ferent vegetable, 

184 

ii 

sea-weed,  uses  of,  as  a. 

169 

11 

saw-dust  and  bran,  as  a. 

176 

(1 

brewers'     grains,    malt 

and  rape  dust. 

177 

II 

hemp,  poppy,  and  cotton 

cakes,  . 

173 

(( 

peat,  peat  compost,  and 

tanners'  bark. 

178 

II 

fermented  and  charred 

peat,    .        .        179, 

180 

11 

charcoal,  soot,  and  coal- 

tar. 

181 

ii 

immediate  and  perma- 
nent effects  of  vege- 

table manures. 

186 

II 

animal,  fish. 

187 

II 

blood  as  a, 

189 

II 

skin,  bone,  hair,  wool, 

190 

II 

nitrogen  in  animal, 

191 

<i 

cow,  horse,  and  pig, 

204 

<i 

droppings  of  birds. 

205 

ii 

relative  values  of  dif- 

ferent animal. 

213 

ii 

difference  in  animal  and 

vegetable, 

215 

Ii 

causes  of  difference  be- 
tween animal  and  ve- 

getable. 

216 

<i 

saline,  why  required  by 

the  soil, 

236 

II 

how  to  determine  the 

value  of  saline, 

23* 

INDEX. 


s:: 


Manure,    saline,    circumstances 
under      which      thej 
are  to  be  used,       .        238 
"      saline,  specific  action  of 

on  plants,        .        .     240 
"     saline,  action  of  on^ar- 
ticular  parts  and  kinds 
of  plants,         .        .     241 
"     sulphates  and  nitrates, 

mixed,         .        .        243 
"     mixed,  promote  growth, 
'  and      prevent      mil- 

dew,    .        .        246,  24T 
"     soil    can    be    restored 

by,  ...   267 

"  influence  o^  on  wheat 
and  other  com 
crops,  ,  278 

Manuring,  green,        .        .        171 
"        with    dry    vegetable 

matter,        .        .     174 
Matter,   organic    diminishes  in 

the  soil,        .         .         266 
Milk,  properties  and  composition 

of,  .  .  .  312,  360 
"  influence  of  breed  on,  314 
"    of  form  and  constitution 

on,  ...        315 

"    of  kind  of  food  on,        .     316 
"    of  soil  on,  .        .        317 

"  adulteration  of,  .  .318 
"  the  whole  may  be  churn- 
ed, ..  .  320 
"  time  required  for  churn- 
ing, ...  321 
"  why  it  becomes  sour,  326 
"  sugar  of,  acid  of,  .  .  326 
"  acid  of;  how  produced,  327 
"  curdUng  ofj  and  casein,  328 
"  rich  in  nitrogenous  food,  358 
"    value  of  saline  ingredients 

in,  .  .  .  ,  359 
"  a  true  food,  .  .  .360 
•'    removes  bone-earth  from 

the  soil,  ...  362 
"    proportions  of  food  yielded 

by,  ...        368 

Mnshroom,      .        .        .        .301 


N. 


Night-soil,  and  poudrette,        .    203 
Nitrogen,       .        .        .         12,  218 
"      necessity  of,  to  the  plant^    15 
"      forma  in  which  it  enters 

the  roots,     .        .  52 

"      in  animal  manures,         191 
"      necessary  to  the  wheat 

crop,   .        .        .        225 
"      exhaled  by  the  skin  and 

lungs,         .        .         350 


0. 


Oats,  composition  of,         .  .     282 

"    when  to  cut,        .  .        305 

"   and  straw,  oil  in,      .  .     307 

Oil,  in     grain,   hay  and  root 

crops,        .        ,  ,        306 

Organic  bodies,       ...        6 

Oxygen,      .        .        .  .       9,  32 

"      the  body  fed  by,  .    340 


Paring  and  burning,    .        .        268 
Pea,  composition  of,        .        .     288 
"    and  bean,   varying  quali- 
ties of;     .        .        .        291 
Peat,  use  o^    .        .        .        -     178 
V    fermented,  .        .        .        179 
"    charred,  as  an  absorbent,     180 
"    ashes,    composition  oi,        235 
Perspiration,  waste  in  animal,      349 
Phosphate,  how  formed,  34,  67 

"         ammoniaco-magne- 

Bian,       .        .        202 
"         of    lime    (and    na- 
tive,)     .        229,  230 
"        experiments  with 

mixed,  .        .        245 
"         of  lime  in  limestone,  252 
Phosphorus,    ....        * 
Physiology,  what  it  will  do  for 
agriculture. 


INDEX. 


Plants,  organic  parts  of,  .        13,  14 
"     structure  of  stem,  root 

and  leaf  ofj    .        .  36 

"     functions  of  roots  of,  37 

"  "        of  the  leaf  of;       37 

"  "        of  the  stem  of,     39 

"     substances  of  which  they 

consist,         .        .  39 

"  structure  of  their  seeds  41 
"  fatty  substance  of;  .  44 
"      waxes  and  resins  of,  45 

"     growth  of,        .        .  47 

"  woody  matter  of,  .  49 
"  source  of  earthy  matter  of,  54 
"      select  the  soils  On  which 

they  prefer  to  grow,      130 
"      sicken  on  some  soils,         132 
Plow,   subsoil,   how  it  acts  in 

improving  the  soil,      147 
"      results  of  experiments 

with,    .        .        149,  150 
Plowing,     deep,    how    it    im- 
proves the  soil,         158 
"        chemical  effects  o^       153 
Potash,  .        .        .        .55 

"     nitrate  of,  .        .  30 

Potato,     average     composition 

of,  .        ..        294,  295 

"  influence  of  variety  on,  296 
"  effect  of  manures  on,  297 
"      effects  of  keeping,   and 

frost  on,         .        .        298 
Poudrette,       .        .        .        .203 


R 

Bags,  woollen,  as  manure,     191,  214 
Bain,  effects  of  on  the  soil,  •       144 
"    causes  the  air  to  be  re- 
newed,   .        .        .        144 
"    warms  the  under  soil,  144 

"    equalizes  the  temperature,  145 
"    carries  down  soluble  sub- 
stances, .        .        .        145 
"    washes  out  noxious  mat- 
ters,   ....     145 
•*    brings    down    fertilizing 

substances  .        ,146 


Rain,  mechanical  action  o^        162 
Rape-dust,  as  manure,        .         177 
"         cake  value  o^        .     289 
Rennet,  action  of,        .        .        329 
Respiration,  effects  of;      .        .216 
Rice,  composition  o^    .        .        287 
Rivers,  English  and  Indian,         277 
Rocks,  -crumbling  of,        .        .      82 
"     constancy    in    minera. 
character  among   the 
stratified,       .        .  85 

"     the  crag,       ...       92 
"     the    plastic    clays    aud 

chalks,  .        .  93 

"     the  green  sand,     .        .      94 
"     the  wealden  formation,       95 
"     the  upper,   middle,    and 
lower  oolite  and   the 
leas,  ...       96 

"  the  new  red  sand-stone, 
the  magnesian  lime- 
stone, aud  the  coal 
measures,      .        .  97 

"     the  mill-stone  grit,  the 
mountain  Kmcstone, 
and  old  red  sandstone,  98, 99 
"     the  upper  and  lower  Sil- 
urian system,        .         100 
"     the  Cambrian,  mica  slate 

and  gneiss  systems,     .  101 
"     granite,  composition  of,     104 
"     quartz,  felspar,  trap  and 
hornblende     composi- 
tion of;       ,        .     105,  106 
"     rotten  rock,  marl,      .        107 
Rye,  composition  of,        .        .287 
"    varying  quality  of|       .        291 


Sal-ammoniac,         .        .  .    224 

Salt,  common,      .        .        .  227 

Salts,  Glauber's,      .        .  .228 

"    Epsom,       ...  228 

Sap,  cause  and  motion  ot  .      39 

"   changes  as  it  ascends,  .  48 

Saw-du8t,  value  of;          .  .     17fi 


INDEX. 


819 


Science  and  practice,  close  con- 
nection between,    .        .        358 
Sea-weed  and  straw,  ashes  of,      321 
Seeds,  structure  of,       .        .  41 

"  germination  of,  .  .  47 
"     steeping  of  in  salts  of 

ammonia,       .        .        224 
Sheep,  sulphur  in  their  wool,      363 

Silica, 55 

Silicate  of  potash  and  soda,         228 
Skin,  carbonic  acid  and  nitrogen 

from,         .        .        .        350 

Soda^ 55 

"    nitrate  of,     ...  30 

"  and  potash,  carbonate  o^  226 
"  sulphate  of  (Glauber's  salts),  328 
"   sulphate    and    nitrate    o^ 

mixed,  .        .        .     543 

Soils,  benefit     from     analysis 

0^  .  .  3,  122,  123 
"    organic  part  of,    .        .  74 

"  inorganic  part  ofj  .  .  75 
"  saline  or  soluble  portion  of,  76 
"    earthy  or  insoluble  portion 

of,  ....  77 
"  sandy,  loamy,  and  peaty,  78 
"  diversities  of,  and  subsoil,  79 
"  origin  of,  ...  82 
"  aiust  of  the  diversity  o%  82 
"    differences  of,  on  stratified 

rocks,  ...       89 

"    density,    and    absorbent 

power  o^  .  .  117 
"    evaporative    power    and 

shrinkage  of,  .        .        118 
"    absorption  of  moisture  of 
the  air  by,  and  tempera- 
ture of.    ...        119 
"    chemical  composition  of      121 
"    fertile  and   barren    com- 
pared,    .        .        .        124 
"    causes  of  the  fertility  of 

black,  .  .  .129 
"    connection  between   and 

plants,  .  .  .129 
*^  general  improvement  of,  135 
*  two  classes  of,  .  .  136 
"    liable  to  be  burned  up,        139 


Soils,  improvement  ofby  mixing,  154 
"  "         by  planting,     156 

"  "  -      by  laying  down 

to  grass,  152 
Soot,  uses  oij  .  .  .  .  189 
Starch  and  gluten,  quantities  of 

in  crops,  .  305 

Straw,  ashes  of,  .  .  .  231 
"  and  hay,  .  .  .301 
"    affected  by  the  time  of 

cutting,         .        .        304 

Subsoil,  importance  of|     .        .80 

"      effects  of  bringing  it  up,  152 

Sulphate,  how  formed,        .    34,  56 

"        of  ammonia,    .        .224 

"        of  potash,    .        .        227 

"        of  soda,    (Glauber's 

salts,)       .        .        228 
"        of  magnesia,  (Epsom 

salts,)  .        .     228 

"        of  iron,  (green  vitrei,)  228 

"        of  lime,  (gypsum,)       229 

"        of  soda  with  nitrates,  243 

Sulphur,         ...     9,  56,  363 

Sulphuric  acid,  ...  33 

"        influence  of  on  crops,  196 

Super-phosphate  of  lime,        34^  230 


Table- 


of  sugars,  ...  43 

of  the  ash  of  plants,  59,  60 
of  hornblende  and  felspar,  106 
of  soils,  .  .  125,  128 
of  experiments  with  tur- 
nips, barley,  and  po- 
tatoes, .  .  149.  150 
of  dry  food  and  farm-yard 

dung,  .  .  .  175 
of  peat  compost,  .  .180 
of  farm-yard  manure  and 

guano,     .        .        .        180 
of  wheat  dressed  with  soot,  182 
of  the  relative  fertilizing 
and    money  values    of 
different  vegetable  ma- 
nures,     .        .        184,  186 


m 


INDSX. 


Table  of  horn  and  bones,        .     192 
"    of  experiments  with  gu- 
ano,       ...        207 
"    of    comparison  of    man- 

nures,      .        .        213,  214 
"    of   carbon    and  nitrogen 
taken^  in  the  food  and 
respired,         ,        .        217 
"    of  experiments  with  salts 

of  ammonia,  .        .         225 
"    of    composition    of   peat  • 

ashes,         .        .        .    ^235 
"    of  mixed  sulphates  and 

nitrates,      .        .        .     244 
"    of   mixtures    promoting 

growth,  .  .  .  246 
"  and  preventing  mildew,  247 
"  of  artificial  guano,  .  248 
"  of  composition  of  lime- 
stone, .  *.  .  251 
"    of  lime  carried  away  by 

crops,      .        .        .         259 
"    of  the  effect  of  equal  quan- 
tities of  manures,     .         279 
"    of  composition  of  wheat,  280-1 
"    of  composition  of  the 

oat,  .        .        282,  283 

"  of  composition  of  bar- 
ley, .  ~  .  284,  285 
"  of  composition  of  rye,  287 
"  of  "  rice,  .  287 
"  of  "  corn,  .  .  287 
"  of  "  buckwheat  287 
"    of       "        the  bean  and 

pea,  .  288 
"    of       "        linseed   and 

cake,  .  289 
"  of  "  the  acorn,  290 
"  of  "  the  turnip,  294 
"  of  "  the  potato,  294 
"  of  "  the  cabbage  300 
•»  of  '•  the  cauliflower,  301 
"    of       "        hay,     straw, 

leaves,         301 
"     of         '        fruits,        .         302 
•'    of  relative  quantities    of 
starch   and    gluten    in 
cultivated  crops,      .        305 


Table   of  proportion  ol.  oil  ir. 

plants,     .        .        ,        BC 
"    of  quantity  of  food  yield- 
ed by  an  acre  of  land,     305 
"    of  composition    of    that 

food,  .  .  .  30€ 
"  of  composition  of  mUk,  313 
"  of  "  c-eam,  .  319 
"    of        "        butter,  322 

"    of       "        fibrin,    or 

muscle,  342 

"    of        "        saline  matter 

in  the  body,  344 
"of        "        mineral  mat- 
ter,       .        345 
"    of        "        food  given  in 
Scotch  pris- 
ons,      .         357 
"    of  food  required  daily  by 

animals,  .        .        358 

"    of   composition  of  cow's 

milk,  .  .  .  360 
"    of  value  of  different  kinds 

of  food,  ...  364 
Taffo,  Chinese,  night-soil,  .  204 
Tanks,  for  liquids,  construction 

of,         ...        200 
"    Tanners' bark,        .        .178 
Trees,  why  different  kinds  suc- 
ceed each  other,     .        131 
"    the  peach  in  New  Jersey,    131 
"    effects  of  the  Scotch  fir 
and   beech  on  pasture 
land,       ...        156 
"    action  of,  in  improving  the 

soil,  ...  158 
Trenching,  how  it  improves  the 

soil,  .  160,  153 
Tull,  Jethro,  experiments  ofj  153 
Turnip,  composition  o^         294,  295 


U. 

Urine;  means  of  preserving  and 

applying  it,  .  .  197 
"  of  man,  .  .  .198 
•'     of  the  pig  and  cow,        199 


INDEX. 


381 


'  rine,  sulphated,       .        .  201 

"     solid  matters  escape  from, 

the 350 

"     salts  and  nitrogen  in,        35^1 

Urate,  how  to  form  a,  .        201 


Vegetable  products,  analyses  of,      3 

Vitriol,  oil  ofj  .         .         .         9 

"     green,  sulphate  of  iron,     228 


W. 

Water,  composition  o^         .  25 

"     its  relations  to  vegetable 

life,       ...  26 

"      differs  in  natural  virtue,    275 
"      effefits  of  dift'erent  springs 

of;        .        .        .        276 
Weeds,  fire,  what  soils  they  like,  130 


Weeds  sea,  uses  of,  .  .  172 
"  special  action  of,  .  173 
"  sea,  ashes  of  and  straw,  231 
Wells,  in  Alabama,  .  .  114 
Wheat,  average  composition  ofj  280 
"  influence  of  climate  on,  280 
"      influence  of  the  kinds  of 

manure  on,  .        281 

"      varying  quality  of,         291 

"      when  to  cut  it,        .        304 

"      flour,  oil  in,        .        .     307 

Winds,  effects  of  in  improving 

the  soil,        .        .        164 
Wool,  growing,  its  effects  on  the 

soil,       ...        362 
"     varied    by  climate   and 

food,      ...        363 
"     and  hair,  5  per  cent,  sul- 
phur,   ...  14 
Worms,  earth,  effect  of  aa  labor- 
ers,    .        .        .        163 
"      quantity  0^         .        .    164 


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